Shadow The Hedgehog

Expert mode:
Get "A" ranks in all stages in the game.

Last Story:
Successfully complete every sixth stage in story mode, defeat all Bosses at the end (all five Hero and all five Dark Bosses), and see all ten Hero and Dark story line endings.
ScionCrow.

Egg Vacuum:
Successfully complete the Neutral story line with the Hero ending.

Use the Egg Vacuum to suck up 20 objects (enemies, etc.) to gain an extra life.
Krystal Tysias.

Get all Neutral endings, then end by getting to the center of Ivan Robotnick's (Eggman's) base. You will get the Egg Vaccum. Do this again only in Dark ending and it will be level 2.
Ethan Anderson.

Heal Cannon:
Successfully complete the Hero story line.

Omochao Gun:
Successfully complete the Semi Hero story line.

Samurai Blade:
Successfully complete the Dark story line

Satellite Laser:
Successfully complete the Semi Dark story line

Shadow Rifle:
Successfully complete the Last Story.

After defeating Devil Doom, you will get the Shadow Rifle. It can help you a lot in Lethal Highway, Air Fleet and Iron Jungle. It can kill normal enemies in one hit within a few minutes (and free shots, like when the alien tank stops, the escape pod slows, or the enemies have been cleared near the Egg Balloon). The targets will be obliterated.
Ethan Anderson.

Level 2 weapons:
Successfully complete both the Hero and Dark versions of a story line.

Songs:
Complete the indicated task to unlock the corresponding song.
brld hvct wabp.

Air Fleet Theme: Play the Air Fleet level.
All Of Me: Successfully complete the Last Story.
All Hail Shadow: Successfully complete the Hero story line.
Almost Dead: Successfully complete the Dark story line.
Black Bull Boss Theme: Defeat Black Bull.
Black Comet Theme: Play the Black Comet level.
Black Doom Boss Theme: Defeat Black Doom.
Central City Theme: Play the Central City level.
Chosen One: Successfully complete the Semi Hero story line.
Circus Park Theme: Play the Circus Park level.
Cosmic Fall Theme: Play the Cosmic Fall level.
Cryptic Castle Theme: Play the Cryptic Castle level.
Death Ruins Theme: Play the Death Ruins level.
Devil Doom Boss Theme: Defeat Devil Doom.
Diablon and Sonic Boss Theme: Defeat those Bosses.
Digital Circuit Theme: Play the Digital Circuit level.
Egg Breaker Boss Theme: Defeat Egg Breaker.
Egg Dealer Theme: Defeat Egg Dealer in the Neutral story line.
Ending: Defeat Devil Doom.
Event 1 Theme: Listen to the Event 1 Theme in story mode.
Event 2 Theme: Listen to the Event 2 Theme in story mode.
Event 3 Theme: Listen to the Event 3 Theme in story mode.
Event 4 Theme: Listen to the Event 4 Theme in story mode.
Final Haunt Theme: Play the Final Haunt level.
Glyphic Cannon Theme: Play the Glyphic Cannon level.
Gun Fortress Theme: Play the Gun Fortress level.
Heavy Dog/Blue Falcon Remixed Boss Theme: Defeat those Bosses.
Iron Jungle Theme: Play the Iron Jungle level.
Lava Shelter Theme: Play the Lava Shelter level.
Lethal Highway Theme: Play the Lethal Highway level.
Lost Impact Theme: Play the Lost Impact level.
Mad Matrix Theme: Play the Mad Matrix level.
Never Turn Back: Complete the Last Story in the Dark story line.
Prison Island Theme: Play the Prison Island level.
Sky Troops Theme: Play the Sky Troops level.
Space Gadget Theme: Play the Space Gadget level.
The Ark Theme: Play The Ark level.
The Doom Theme: Play The Doom level.
The Final Way: Play The Final Way level.
Waking Up: Complete the Neutral story line.
Westopolis Theme: Play the Westopolis level.

Key bonuses:
Collect all five hidden keys in the indicated level to unlock the corresponding bonus behind the five-keyed doors.

Air Fleet: Air Saucer
Black Comet: Two turrets
Central City.: Air Saucer
Circus Park: Extra shooting gallery
Cosmic Fall: Switch that makes ring trails to the end of the level
Cryptic Castle: Shortcut
Death Ruins: Warp Portal
Digital Circuit: Warp Portal
Final Haunt: Turrets
Glyphic Canyon.: Black Arm's Vehicle
GUN Fortress.: Military Vehicle
Iron Jungle.: Tank Cannon
Lava Shelter.: Air Saucer
Lethal Highway: Large GUN Cannon
Lost Impact.: GUN Vehicle
Lost Impact: Armored Car
Mad Matrix: Alternate path to red terminal.
Prison Island.: Tank Cannon
Sky Troops.: Black Arm's Vehicle
Space Gadget: Warp Hole
The ARK: Three extra lives
The Doom: Open cage to shortcut to the end of the level
The Last Way: Warp Portal
Westopolis.: Armored car

Library sequences:
Complete the indicated path of story mode missions to unlock the corresponding intermission sequences at the Library.
Cinnamon and Arnold Rimmer.

231: I Am The Strongest!: Neutral, Hero, Hero, Hero, Hero, Dark ending
1: Punishment, Thy Name Is Ruin: Dark, Dark, Dark, Dark, Dark, Dark, Dark final Boss
2: Prologue To World Conquest: Dark, Dark, Dark, Dark, Dark, Dark, Hero ending
3: The March To A Darker World: Dark, Neutral, Dark, Neutral, Hero, Dark
4: The Ultimate Ego: Dark, Dark, Dark, Dark, Hero, Hero
5: Purification Via Ruination: Dark, Dark, Dark, Hero, Dark, Dark ending
6: Apogee Of Darkness: Dark, Dark, Dark, Hero, Dark, Hero ending
7: True Soldier Of Destruction: Dark, Dark, Dark, Hero, Neutral, Dark ending
8: Believe In Yourself: Dark, Dark, Dark, Hero, Neutral, Hero
9: An Android's Determination: Dark, Dark, Dark, Hero, Hero, Dark
10: For Machine, By Machine...: Dark, Dark, Dark, Hero, Hero, Hero
11: Revenge At Last: Dark, Dark, Neutral, Dark, Dark, Dark ending
12: Ego's Awakening: Dark, Dark, Neutral, Dark, Dark, Hero
13: Destruction and Scorn: Dark, Dark, Neutral, Dark, Neutral, Dark
14: The Last Remaining Purpose: Dark, Dark, Neutral, Dark, Hero, Hero
15: The Nightmare's Insulation: Dark, Dark, Neutral, Neutral, Dark, Dark ending
16: The Nightmare's Sublimation: Dark, Neutral, Neutral, Neutral, Dark, Hero
17: The Loner's Choice: Dark, Dark, Neutral, Neutral, Neutral, Dark
18: Subjugation In Black: Dark, Neutral, Neutral, Neutral, Neutral, Neutral
19: Replica's Depression: Dark, Dark, Neutral, Neutral, Hero, Dark
20: Machine, Machine: Dark, Dark, Neutral, Neutral, Hero, Hero
21: Disciple from the darkness: Dark, Dark, Neutral, Hero, Dark, Dark
22: Beloved Clone: Dark, Dark, Neutral, Hero, Dark, Hero
24: The Ultimate Replica: Dark, Dark, Neutral, Hero, Neutral, Hero
25: Sanction's Demise: Dark, Dark, Neutral, Hero, Hero, Dark
26: Along With My Home: Dark, Dark, Neutral, Hero, Hero, Hero
27: The Cleansing of Darkness: Dark, Dark, Hero, Dark, Dark, Dark
28: Birth of a God: Dark, Dark, Hero, Dark, Dark, Hero
29: The Last Soldier's Grim Fate: Dark, Dark, Neutral, Hero, Dark, Dark
30: Isolation and Solitude: Dark, Dark, Hero, Dark, Neutral, Dark
31: Archimedes and the Tortoise: Dark, Dark, Hero, Dark, Neutral, Hero
32: Where Is My Happiness?: Dark, Dark, Hero, Dark, then all hero
33: Seduced by Taste of Blood: Dark, Dark, Hero, Dark, Hero, Dark
37: Last Will and Testament: Dark, Dark, Hero, Neutral, Neutral, Dark
38: Enveloped in Solitude: Dark, Dark, Hero, Neutral, Neutral, Hero
39: Parricidal Savior: Dark, Dark, Hero, Neutral, Hero, Dark
43: The Ultimate Confrontation: Dark, Dark, Hero, Hero, Hero, Dark
44: Miracle of Love: Dark, Neutral, Hero, Hero, Hero, Hero
45: The World's Demise: Dark, Hero, Dark, Dark, Dark, Dark ending
48: Vainglory or Abandonment?: Dark, Hero, Dark, Dark, Neutral, Hero ending
50: Standing at the Summit: Dark, Hero, Dark, Neutral, Dark, Hero
51: Controller from the Capsule: Dark, Hero, Dark, Neutral, Neutral, Dark
52: Beyond One's Own Power...: Dark, Hero. Dark, Neutral, Neutral, Good.
53: A Clone's Determination: Dark, Hero, Dark, Neutral, Hero, Dark.
55: A Toast To The Ruler: Dark, Hero, Dark, Hero, Dark, Dark
56: Answer from the Black Comet: Dark, Hero, Dark, Hero, Dark, Hero
57: Transcendentalism: Dark, Hero, Dark, Hero, Neutral, Dark.
59: The Weight of One's Crimes: Dark, Hero, Dark, Hero, Hero, Dark
64: To Love Oneself: Dark, Hero, Neutral, Dark, Neutral, Hero
66: Birth of The Robot Emperor: Dark, Hero, Neutral, Dark, Hero, Hero
68: A Solitary Android: Dark, Hero, Neutral, Neutral, Dark, Hero
69: Over the Original: Dark, Hero, Neutral, Neutral, Neutral, Dark
70: Machine Sunshine: Dark, Hero, Neutral, Neutral, Neutral, Hero
77: The Legend of Shadow: Dark, Hero, Neutral, Hero, Hero, Dark
78: Power Of Love: Dark, Hero, Neutral, Hero, Hero, Hero
80: Walk My Way: Dark, Hero, Hero, Dark, Dark, Hero ending
82: A Monarch's Style: Dark, Hero, Hero, Dark, Neutral, Hero
84: To Be Ignorant of the Past: Dark, Hero, Hero, Dark, Hero, Hero
91: The Rise and Fall Of The ARK: Dark, Hero, Hero, Hero, Dark, Dark
92: Requiem for a Fallen Angel: Dark, Hero, Hero, Hero, Dark, Hero
93: Ultimate Shadow: Dark, Hero, Hero, Hero, Hero, Dark
94: For Love's Sake: Dark, Hero, Hero, Hero, Hero, Hero
95: A Heart Awoken from Darkness: Neutral, Dark, Dark, Dark, Dark, Dark
96: Destruction From Perfection: Neutral, Dark, Dark, Dark, Dark, Hero
97: Darkness' Strongest Soldier: Neutral, Dark, Dark, Dark, Hero, Dark
98: Severed Chains: Neutral, Dark, Dark, Dark, Hero, Hero.
100: To Be Known as "Ultimate": Neutral, Dark, Dark, Neutral, Dark, Hero
101: Dark Warrior's Advent: Neutral, Dark, Dark, Hero, Neutral, Dark
102: Arriving At The Ego: Neutral, Dark, Dark, Hero, Neutral, Hero ending
103: Determination Of A Fake: Neutral, Dark, Dark, Hero, Hero, Dark
104: Path to the Machine's Empire: Neutral, Dark, Dark, Hero, Hero, Hero
105: Demise Wrought by Tragedy: Neutral, Dark, Neutral, Dark, Dark, Dark
106: Turning Sorrow into Strength: Neutral, Dark, Neutral, Dark, Dark, Hero
107: The Liberated Soldier: Neutral, Dark, Neutral, Dark, Hero, Dark
108: Stupefaction's End: Normal, Dark, Normal, Dark, Hero, Hero
109: Humanity's Folly: Neutral, Dark, Neutral, Neutral, Dark, Dark
110: Surpassing All Else: Neutral, Dark, Neutral, Neutral, Dark, Hero Ending
111: Soldier Of Grief: Neutral, Dark, Neutral, Neutral, Neutral, Dark ending
112: Reclaimed Heart: Neutral, Dark, Neutral, Neutral, Neutral, Hero
113: Fighting Spirit of Steel: Neutral, Hero, Neutral, Neutral, Dark, Dark
114: Machine Soldier Uprising: Neutral, Dark, Neutral, Neutral, Hero, Hero
115: The Devil Born From Betrayal: Neutral, Dark, Neutral, Hero, Dark, Dark
117: The Immortal Android: Neutral, Dark, Neutral, Hero, Neutral, Dark
118: The New, Coldhearted Empire: Neutral, Dark, Neutral, Hero, Neutral, Hero
120: Spawn Of The Devil: Neutral, Dark, Dark, Hero, Hero, Hero ending
121: Black Doom's Scheme: Neutral, Dark, Hero, Dark, Dark, Dark ending
122: Subjugating Heaven and Earth: Neutral, Dark, Hero, Dark, Dark, Hero
123: Road of the Dark Soldier: Neutral, Dark, Hero, Dark, Neutral, Dark
124: Dark Finale: Neutral, Dark, Hero, Dark, Neutral, Hero
125: Realization While On Board: Neutral, Dark, Hero, Dark, Hero, Dark ending
126: Birth of a Champion: Normal, Dark, Hero, Dark, Hero, Hero
128: The Road To Self-Assurance: Normal, Dark, Hero, Normal, Dark, Hero
130: Surpassing His Creator: Neutral, Dark, Hero, Neutral, Neutral, Hero
131: ARK. Colony of Pathos: Neutral, Dark, Hero, Neutral, Hero, Dark
135: A Vow For The Victims: Neutral, Dark, Hero, Hero, Neutral, Dark
137: The Destined Sonic Showdown: Neutral, Dark, Hero, Hero, Hero, Dark
138: The Black Hero's Rebirth: Neutral, Dark, Hero, Hero, Hero, Hero
139: Truth, Thy Name is Vengeance: Neutral, Netural, Dark, Dark, Dark, Dark
140: Searching for 'Ultimate': Netural, Neutral, Dark, Dark, Dark, Hero
141: Reborn Hatred for Humanity: Neutral, Neutral, Dark, Dark, Hero, Dark
142: A Future Taken From the Past: Neutral, Neutral, Dark, Dark, Hero, Hero
144: One To Succeed A God: Neutral, Neutral, Dark, Neutral, Dark, Hero ending
145: Disappointed In Humanity: Neutral, Neutral, Dark, Neutral, Neutral, Dark
146: Faith Taken From Solitude: Neutral, Neutral, Dark, Neutral, Neutral, Neutral, Hero final Boss
146: Faith Taken From Solitude: Neutral, Neutral, Dark, Neutral, Neutral, Neutral, Hero ending
148: To unite humanity: Neutral, Neutral, Dark, Dark, Hero, Hero
153: Together With Maria...: Neutral, Neutral, Dark, Hero, Hero, Dark ending
154: The Tragedy's Conclusion: Neutral, Neutral, Neutral, Dark, Hero, Hero, Hero ending
155: The Day That Hope Died: Neutral, Neutral, Neutral, Dark, Dark, Dark
156: Dark Destroyer: Neutral, Neutral, Neutral, Dark, Dark, Hero
157: Diabolical Power: Neutral, Neutral, Neutral, Dark, Neutral, Dark ending
158: For Freedom: Neutral, Neutral, Neutral, Dark, Neutral, Hero
159: At Least, Be Like Shadow...: Neutral, Neutral, Neutral, Dark, Hero, Dark
160: Seeking A Silent Paradise: Neutral, Neutral, Neutral, Dark, Hero, Hero
161: The Lion's Awakening: Neutral, Neutral, Neutral, Neutral, Dark, Dark ending
162: Identity: Neutral, Neutral, Neutral, Neutral, Dark, Hero ending
163: An Android's Rebellion: Neutral, Neutral, Neutral, Neutral, Neutral, Dark
164: A New Empire's Begining: Neutral, Neutral, Neutral, Neutral, Neutral, Neutral, Hero final Boss
165: Bullets From Tears: Neutral, Neutral, Neutral, Neutral, Hero, Dark ending
166: Journey To Nihility: Neutral, Neutral, Neutral, Neutral, Hero, Hero
168: Dr. Eggman's Miscalculation: Neutral, Neutral, Neutral, Hero, Dark, Hero
169: Along With The ARK: Neutral, Neutral, Neutral, Hero, Neutral, Dark
170: Requiem For The Heavens: Neutral, Neutral, Neutral, Hero, Neutral, Hero ending
171: Sonic Dethroned: Neutral, Neutral, Neutral, Hero, Hero, Dark
172: Justice Reborn in Space: Neutral, Neutral, Neutral, Hero, Hero, Hero
175: Farewell To The Past: Neutral, Neutral, Hero, Dark, Neutral, Dark ending
177: The Guardian With No Past: Neutral, Neutral, Hero, Dark, Hero, Dark ending
180: Machine World: Neutral, Neutral, Hero, Neutral, Dark, Hero
182: Compensation For A Miracle: Neutral, Neutral, Hero, Neutral, Neutral, Neutral, Hero final Boss
183: The Strongest Hedgehog: Neutral, Neutral, Hero, Neutral, Hero, Dark
185: Voyage of Reminiscence: Neutral, Neutral, Hero, Hero, Dark, Dark
186: Wandering's End: Neutral, Neutral, Hero, Hero, Neutral, Hero
184: The Ultimate Punisher: 3 Neutral, Hero, Neutral, Hero, Hero.
188: Punisher of Love: Neutral, Neutral, Hero, Hero, Hero, Hero
189: Messenger From the Darkness: Neutral, Hero, Dark, Dark, Dark, Dark
190: The New Ruler: Neutral, Hero, Dark, Dark, Dark, Hero.
191: Dark Soldier: Neutral, Hero, Dark, Dark, Neutral, Dark.
193: The Machine-Laden Kingdom: Neutral, Hero, Dark, Dark, Hero, Dark ending
195: Birth Of The Dark Soldier: Neutral, Hero, Dark, Neutral, Dark, Dark
201: A Hero's Resolution: Neutral, Hero, Dark, Hero, Dark, Dark
203: Perpetual Voyage: Neutral, Hero, Dark, Hero, Neutral, Dark
206: And the Dream Continues: Neutral, Hero, Dark, Hero, Hero, Hero ending
208: The Path I Believed In: Neutral, Hero, Neutral, Dark, Dark, Hero
210: Machine Kingdom at Dawn: Neutral, Hero, Neutral, Dark, Neutral, Hero
211: Sinful Protector: Neutral, Hero, Neutral, Dark, Hero, Dark
215: Wandering For Eternity: Neutral, Hero, Neutral, Neutral, Neutral, Dark ending
216: At Vagrancy's End: Neutral, Hero, Neutral, Neutral, Neutral, Hero ending
217: The Summit of Power: Neutral, Hero, Neutral, Neutral, Hero, Dark ending
218: Under the Name of Love: Neutral, Hero, Neutral, Neutral, Hero, Hero
219: Eternally Drifting: Neutral, Hero, Neutral, Hero, Neutral, Dark ending
220: The Importance of Truth: Neutral, Hero, Neutral, Hero, Neutral, Hero ending
222: This World'd Guardian: Neutral, Hero, Neutral, Hero, Hero, Hero ending
223: Light Born from Darkness: Neutral, Hero, Hero, Dark, Dark, Dark
224: The Order of Steel: Neutral, Hero, Hero, Dark, Dark, Hero
225: Solitary Journey: Neutral, Hero, Hero, Dark, Neutral, Dark
226: The Fall Home: Neutral, Hero, Hero, Dark, Neutral, Hero
228: I Shall Be The One To Judge: Neutral, Hero, Hero, Dark, Hero, Hero ending
229: Gone With The Darkness: Neutral, Hero, Hero, Neutral, Neutral, Dark
230: The Ultimate Choice: Neutral, Hero, Hero, Neutral, Dark, Hero
232: Justice's Awakening: Neutral, Hero, Hero, Hero, Hero, Hero ending
233: Prelude to Ruination: Hero, Dark, Dark, Dark, Dark, Dark
236: To Just Be Myself: Hero, Dark, Dark, Dark, Hero, Hero
237: Punishment in Jet Black: Hero, Dark, Dark, Neutral, Dark, Dark
240: The Faint Light of Tomorrow: Hero, Dark, Dark, Neutral, Neutral, Hero.
241: Time of Departure: Hero, Dark, Dark, Neutral, Hero, Dark
242: Rise of the Machine Kingdom: Hero, Dark, Dark, Neutral, Hero, Hero
245: Setting Out in the Morning: Hero, Dark, Dark, Hero, Normal, Dark
248: Making Up For it in the End: Hero, Dark, Dark, Hero, Hero, Hero
252: Howl of Solitude: Hero, Dark, Neutral, Dark, Neutral, Hero
253: Proof of Existence: Hero, Dark, Neutral, Dark, Hero, Dark
254: Ardent Vow: Hero, Dark, Neutral, Dark, Hero, Hero
256: A Reason to Live: Hero, Dark, Neutral, Neutral, Dark, Hero ending
259: A Heart Bound To The ARK: Hero, Dark, Neutral, Neutral, Hero, Dark ending
262: Steel Combat Boots: Hero, Dark, Neutral, Hero, Dark, Dark ending
263: Protector Of The Ashen Moon: Hero, Dark, Neutral, Hero, Neutral, Dark ending
266: I Know The Will Of Heaven: Hero, Dark, Neutral, Hero, Hero
271:The Eternally-Closed Door: Hero, Dark, Hero, Dark, Hero, Dark, Dark ending
275: The Reason You Were Born: Hero, Dark, Hero Neutral, Neutral, Dark
276: The Dark Part Of The Galaxy: Hero, Dark, Hero, Neutral, Neutral, Hero.
278: Maria's Testament: Hero, Dark, Hero, Neutral, Hero, Hero
279: A Genius Scientist's Lineage: Hero, Dark, Hero, Hero, Dark, Dark
282: Beloved Memories: Hero, Dark, Hero, Hero, Hero, Hero
283: Birth Of A Devil: Hero, Hero, Dark, Dark, Dark, Dark
284: A Dark Myth's Beginnings: Hero, Hero, Dark, Dark, Dark-Hero ending
285: Black Thunder: Hero, Hero, Dark, Dark, Neutral-Dark ending
287: A Soul Sheltered By Iron: Hero, Hero, Dark, Dark, Hero-Dark ending
288: Steel Nation's Decree: Hero, Neutral, Dark, Dark, Hero, Hero
291: The Doctor's Lie: Hero, Hero, Dark, Neutral, Neutral, Dark
296: Fullmetal Prince: Hero, Hero, Dark, Hero, Dark-Hero ending
299: Charm of The Chaos Emeralds: Hero, Hero, Dark, Hero, Hero, Dark
300: Promise of a Far-Off Day: Hero, Hero, Dark, Hero, Hero, Hero
306: Explanation of the Truth: Hero, Hero, Neutral, Dark, Hero, Hero
309: Funeral Procession In Space: Hero, Hero, Neutral, Neutral, Neutral, Dark
310: Lost to the Universe's Abyss: Hero, Hero, Neutral, Neutral, Neutral, Hero
311: Destiny for Two: Hero, Hero, Normal, Normal, Hero, Dark
312: The Sound Threads of Fate: Hero, Hero, Normal, Normal, Hero, Hero
314: Ghost of The ARK: Hero, Hero, Neutral, Hero, Dark, Hero
315: A Pair of Shooting Stars: Hero, Hero, Neutral, Hero, Hero, Dark
316: The One Who Maria Entrusted: Hero, Hero, Hero, Neutral, Hero, Hero
317: A.1's Enlightenment: Hero, Hero, Hero, Hero, Neutral, Dark, Dark ending
318: A Dying Empire's Cry: Hero, Hero, Hero, Dark, Dark, Hero
319: Moon of Atonement: Hero, Hero, Hero, Dark, Neutral, Dark
320: Tear-Soaked Hometown: Hero, Hero, Hero, Dark, Neutral, Hero ending.
321: Sparks On The Horizon: Hero, Hero, Hero, Dark, Hero, Dark ending
322: A Use For A Saved Life: Dark, Neutral, Dark, Hero, Dark
323: Coffin Of Memories: Hero, Neutral, Hero, Neutral, Dark, Dark
324: The Self-Imposed Seal: Hero, Hero, Hero, Hero, Neutral, Hero
325: Pretense in the Mirror: Hero, Hero, Hero, Hero, Hero, Dark
326: A Missive From 50 Years Ago: Hero, Hero, Hero, Hero, Hero, Hero, Hero final Boss

Full pause screen:
Press Start to pause game play, then hold B.

Hint: Character choices:
In just about all of the stages you have three choices: to help the Dark side, yourself, or the Hero side whenever you have someone with you and it is not a Boss fight. To change the character you want with you, press Start. There will most likely be three selections: Dark, Neutral, and Hero. Press Left or Right to highlight a character or ring in the middle. Press A to select the highlighted character. That character will remain with you until your next run in with the other character. You can then simply press Start and do the process again. Note: You cannot select a Hero partner if there is an "X" over the Hero side. You cannot select a Dark partner if there is an "X" over the Dark side.
Mike2 Gremillion.

Another way to do this is to use the D-Pad on the controller during the game. Press Right for the Hero character, Left for the Dark character, and Down for the Neutral character.
ScionCrow.

Hint: Hyper Shadow:
In order to turn into Hyper Shadow you first need to complete all the endings for all the stories. This includes the good and evil storylines. Once you do this, you will unlock the Last Story. Choose the Last Story and you will begin a level called The Last Way after some intermission sequences. Once you complete this and reach Black Doom, there will be an intermission sequence, at the end of which Shadow takes the Chaos Emeralds and turns into Hyper Shadow.
madcommie.

To defeat Devil Doom as Hyper Shadow, hold X to charge Chaos Spear and hit it numerous times. Get lots of rings and you will survive.
Ethan Anderson.

Hint: Shadow Androids:
In versus mode, there are four Shadow Androids. Two have machine guns and two have rocket launchers. They have unlimited ammunition but cannot pick up other weapons.
Ethan Anderson.

Hint: Renegade as name:
Do fifteen Dark missions and two Hero missions. When Eggman or Doom's Eye speaks to you, will be refereed to as ''Renegade".
ZacComicMan.

Hint: Pure Heart as name:
Do fifteen Hero missions. Every once in awhile Sonic, Tails, and Amy will refer to you as ''Pure Heart''. You will not be called that if you do a Dark mission.
ZacComicMan.

Hint: The Ark: Independence Day reference:
If you finish The Ark level with the Dark objective, an intermission sequence will appear where the Black Arms fire the Eclipse Cannon and hits Central City, starting at the capital, which bears a striking resemblance to the famous Independence Day movie scene where the White house was destroyed.
Kenju.

Hint: The Ark: Ignore the map:
In some of the Ark levels, Shadow tells you to keep an eye on the map. However the map does not say where to go to finish the level, so you are just wasting your time reading it.
supacooldude3000.

Hint: Cryptic Castle: Eggman comment:
In Cryptic Castle, select Amy or Shadow. When you float on the balloon over the three towers, when you reach the middle tower Eggman will say "Try going down".
Ethan Anderson.

Hint: Death Ruins: Black Bull:
Do not bother using the homing attack; it is too hard to get to, and it is difficult to keep hitting him like that. Instead, defeat the two Black Arms soldiers and collect the guns from them. Then, head for the spring and use it. Move forward a bit so you do not start grinding the rails. Pass Black Bull in your jump, and rapidly shoot a little before you level with its eye. Repeat the strategy, and if you fill your Hero gauge, activate Chaos Control and finish him off. This seems easier than to grind around him and shooting him every time around, which wastes ammunition on a lot of missed shots.
Kenju.

Hint: Lethal Highway: Black Bull:
At the start, run up to him and start using homing attacks on the Black Volts to get to his eye. When you hit him once, wait until Shadow comes out of spinning from the recoil and straightens up, then attack again. This will minimize your chances of diving to him and getting hurt instead of another homing attack. Continue this as long as you can. When he is in the middle of the street, there are no Black Volts to bounce on. Instead, run directly under his head, then run away before he creates a shockwave under himself. By doing this, Black Bull will tilt his head down, making it an easy target. When he moves back, repeat. If you get a Gun from Black Arms soldiers, use it, but do not waste it. You will most likely fill your Hero gauge by then. Use it when he is easy to hit, then finish him off. He actually should be fairly easy.
Kenju.

Start by running in the opposite direction that you face. Keep running until you find three monsters with pistols. One of them has a shield. Kill them all and take the pistols. Do not use the pistols yet. Then, attack the little birds and press A repeatedly until the Boss moves out of range. Keep doing this until your Hero Gauge fills. Use Chaos Control and shoot Black Bull.
SONIC.

Hint: Lethal Highway: NiGHTS reference:
In the very start of Lethal Highway, you should see a billboard to the right with an advertisement for a drink or something similar. If you continue watching it, it will switch to a picture of NiGHTS, which will then change to the NiGHTS title.
Kenju.

Hint: Wesopolis: Interesting billboard:
Watch for a sign that reads ''Sonic Team". If you have Doom's Eye as an ally, the sign has red paint over it, and will now read ''Shadow the Hedgehog".
ZacComicMan.

Hint: Boss appearances:
The following is where and how many times you will fight each final Boss:
Ethan Anderson.

Egg Dealer (four times): Lava Shelter (both Bosses), Cosmic fall (Dark Boss), Black Comet(Hero Boss).

Black Doom (three times): Final Haunt (Hero Boss), Cosmic Fall (Hero Boss), GUN Fortress (Hero Boss).

Diablon/Sonic: GUN Fortress (Dark Boss), Black Comet (Dark Boss), Final Haunt (Dark Boss)

Devil Doom: The Last Way (only appearance)

Hint: Defeating Black Bull:
Use the following trick to defeat Black Bull in Death Ruins. Kill lots of soldiers. Then after getting the desired number of bullets, shoot him. When you get Chaos Control, use it and shoot him rapidly. The shots will keep the Hero meter full and you will kill him.
Ethan Anderson.

Hint: Defeating Devil Doom:
Play as Super Shadow and hit him with the Chaos Spear(s). First, try to avoid the meteors that shoot lasers at you, or destroy them if desired. Charge your Chaos Spear with X and blast Devil Doom in the eye. Devil Doom's third eye will go to the other head. Go to the other side and charge your Chaos Spear. Blast him in the eye again. Note: Make sure to shoot the balloons to get rings if you are running low. When you blast him in the eye immediately, go to the other side, and charge your blast . When Devil Doom's third eye gets to the other side of the head, blast him. Go to the other side and blast him, then go to the other side blast him and repeat.
DragonSlayr495.

Hint: Defeating Diablon:
Get a gun then keep attacking when he is on the ground and your Dark meter is full. You will be invincible and have unlimited bullets. This is easier if you have a machine gun of some sort. Hitting him will also increase your Dark meter, making it last longer.
Ethan Anderson.

Hint: Extra ammunition:
Go to the stage were you have to kill the Chaos. There is a room near two GUN soldiers and a Chaos that has two weapon boxes in it. Break both boxes, then go in the room with the GUN soldiers. Go back and the boxes will be back. You can repeat this as many times as desired.
KirbyDeluxe.

Hint: Save lives in Expert mode:
When playing in Expert mode, you must go through all of the levels one at a time without a break or mission, and on a harder difficulty. You are given five lives, any lives you pick up, but cannot continue. If you lose all your lives, you must start all the way back on the first level. However, if you find yourself in a dangerous position (for example, falling off a cliff), press Start before the game registers the loss of the life, then select "Quit". At the Expert mode menu, select "Resume". At the cost of starting at the beginning of the level you were on, you will not lose that life and resume with whatever total you had previously.
Denny Betterman.

Hint: Temporary invincibility:
When your Chaos Control meter is draining, you will be invincible and have unlimited ammunition. This is useful when fighting Bosses, Black Bull, etc.
freakyfriday121 sonic1.

Hint: Recommended weapons:
The weapons in order of best to worst are as follows.
Ethan Anderson.

Shadow Rifle
Samurai Blade
Satellite Laser
Omochao Gun/Heal Cannon (Heal Cannon recommended for The Doom)
Chaingun (most common in Gun Fortress)
Refractor (Elite Black Arms Soldiers)
Homing Missile Launcher (Missle Mech or Soldiers in GUN Fortress)
Worm Launcher (Giant Worms)
Spaz Shotgun (anywhere but level 1)
Egg Vacuum

Hint: Samurai Blade:
The Samurai Blade has a low amount of slashes in level 1, but it kills in one hit due to a shock-wave that comes out of the blade. Like all swords you cannot ride on it, making its use difficult in levels such as Black Comet and Prison Island.
Ethan Anderson.

Hint: Continuos Chaos Blast music:
In two player mode, select either the red or orange Shadow (not the metal Shadows). If you are evil enough you will get "Chaos Blast". Use it, and the game will remain at the Chaos Blast music.
DragonSlayr495.

Hint: Yuji Naka reference:
Sometimes the GUN soldiers will say odd things. One of the things that they say is "Mr. Yuji Naka is all right." Yuji Naka is the creator of the Sonic series.
Cal Lawrence.

Glitch: Floating heal unit:
When you get to the stage with Maria on the Space Colony Ark 50 years before, the hero's mission is to heal all the men to let them escape. You must get shot when you throw it at the person. It will be stuck in the air. Note: If you are planning to do that mission do not perform this glitch.
Garren Davis.