Gundam: Zeonic Front

Alternate styles:
Hold L2 + R2 and press X when selecting a Mobile Suit.

8th MS Team's GM:
Sometimes when you play Iron Spear, you will see a Mobile Suit with the body of a Gundam(G) and the head of a GM. It is similar to the GM from the show 8th MS Team. Note: The Mobile Suit might just be a GM Command.
Suren108.

Amuro Ray's Gundam:
Get "S" or "A" ranks on simulations 27 to 31 to get the same Gundam as Sayla's.
Suren108.

Char Aznable:
Get an "S" rank in Simulation Program 1.

Char is invincible, unless you are hacked at. This is the only person this applies to. Also note that he is not invincible if shot in the back.
Marlin Pryor.

Ensign Niki Roberto's GM Command:
Destroy as many Zeon Mobile Suits as possible, mainly Zakus, with his GM on a Federation simulation. Note: This suit is not good like his GM and it is difficult to win a mission with him. Unlock simulation 33 and use his GM on the simulation 2 alone, no team members because it is easier, and kill all or as many Zakus as you can, including the one with the bazookas.
Shyamal Mishra

Federation GMS:
Successfully complete the game once, then complete practice mission 1 with all the other pilots.
Junhee Lee

Federation Shield for Austin's Zaku 1:
After you complete the game once, play practice mission 1 with Austin's Zaku 1. Successfully complete it and you should have a heavy Fed shield like the Gundam's, and a few new supplies.
Metroid666.

Gaia:
Successfully complete the game, then play again. Complete mission 12 a second time to unlock Gai

Garma Zabi:
Get an "S" rank in Simulation Program 2.

Kai, Hayato, and Lt. Agar:
Successfully complete the game, then play again. Complete the "Attack Jaburo" a second time.

Get an "S" rank on the Federation Simulation mission Burning Sands to unlock Kai and his Guncannon, and Hyato and his Guntank.
Mike Dean.

Kai's Guntank and Hayato's Guncannon:
Destroy as many Zeon Mobile Suits as possible, mainly Zakus, with their original Mobile Suit (Kai's Guncannon and Hayato's Guntank) in a Federation simulation. Note: An easily way is to unlock Simulation 33 and complete simulation 2 alone.
Shyamal Mishra.

LC Garret Schmitzer:
Successfully complete all thirteen missions to unlock LC Garret Schmitzer.

Lt. Agar's Mudrock:
Get one "S" rank on one of the Federations simulations with Lt. Agar's Guncannon to get his prototype Mudrock from mission 10 (Attack Jaburo). To get the fully upgraded Mudrock from mission 12 (Hail Zeon), win another Federation simulation with Lt. Agar's prototype Mudrock.
Suren108.

Lt. Fran's Guntank:
Get an "S" rank on one of the Federations simulations with her GM S-Armor. Note: The easiest way to get it is to get an "S" rank on Burning Sands with her.
Suren108.

Lt. Sandra's Guntank:
Destroy as many Zeon Mobile Suits as possible, mainly Zakus, with her Gundam(G) on a Federation simulation. Note: An easy way is to unlock simulation 33 and use her Gundam(G) on the simulation 2 alone. Kill all or as much Zakus as you can, including the one with the bazookas.
Shyamal Mishra.

Ramba Ral:
Successfully complete the game, then play again. Complete mission 8 a second time to unlock Ramba Ral.

Sayla:
Get three "C" ranks or below on the Federation missions to unlock Sayla.
The Scorpion.

Beam Rifle for Sandra's Dom Tropen:
After successfully completing the game once, get an "S" rank on any simulators except for the Federation simulator and Simulators 1 and 2. Note: You must first unlock a beam rifle for Sandra's Zaku 2. If you did not get the beam rifle after you got an "S" rank with Sandra Dom Tropen, then try another simulators or just keep getting "S" ranks on simulators with her Dom Tropen until you get it
Suren108.

Beam rifle for Sandra's Zaku2:
After successfully completing the game once, get an "S" rank on simulator mission 1.
Junhee Lee.

All simulations:
Successfully complete the game three times. This game will not unlock Simulation 33. After you unlock it, you can play any character on any sim program.
KyroSutona.

Simulation 33:
Get an "S" rank on all missions in rounds 1 and 2 and simulations 1 through 32 to unlock simulation 33. After you unlock it, you can use any Mobile Suit in any simulation (for example, Federation Mobile Suits in Zeon simulations).
Shyamal Mishra.

Additional missions:
Successfully complete the game to unlock another set of missions.
Morgan Shepard.

Successfully mission mode two times on the same file, then check the Simulations. The following missions are now unlocked: Breakthrough II, Midnight Fenrir II, Dobday Rescue II, The Hunter II, Final Defense II, and The Last Fang II.
Mike Dean.

Successfully complete the game twice with the same data to unlock the Federation missions.
Suren180.

Alternate Mobile Suit:
Hold L2 + R2 and use X when choosing a Mobile Suit.

Strafing:
While running, hold L1 and press the Left Analog-stick to the direction that you want to strafe with.
Carrie Johnson.

Hint: Kill units easier:
Try to get behind the enemy, then shoot (or hack) at them.
Zero_X.

Hint: Automatic sniper rifle:
Chose CPO Manning when he has the Reloder III. Equip the Reloder III and chose his sniper rifle. When in combat, you will get fast, unaltered shots. Note: This also works for other weapons, but is best done with the 90mm AR.
PRYO311.

Hint: Practice Mission 1: "S" rank:
Go to the right side through the woods. Once you get behind the enemy, just shoot them from the back and they will not notice you.
Junhee Lee.

Hint: Mission 12: Quick win:
On Mission 12, "Hail Zeon", go south with the Blue Team and destroy any Mobile Suits that get in the way. Then, search the south and southeast area until you find Gundam Mudrock. Once you find it, destroy it and you will win. Sandra's Dom Tropen is recommended, with Beam Rifle, Spray Beam, Armor, and if there is space, add whatever else desired; or any Mobile Suit with a Beam Rifle and Heavy Armor.
Suren180.

Glitch: Sandra's Beam Sabre disappears:
Sometimes when you play in the Federation simulations, Sandra's Gundam(G)'s Beam Sabre will disappear. To get it back, make sure you have her Guntank first, Then, switch to her Guntank and back to Gundam(G).
Shyamal Mishra.