Guilty Gear X2

Clear pause screen:
When in the pause menu in any mode, press Select to get a clear view without the shading or the menu. Press Start to resume game play or Select to return to the pause menu.
Eljay.

Unlimited tension:
When choosing your character, make them SP then press Start. You will have unlimited tension throughout the match.
Xcalibur254.

EX fighters:
Defeat an EX character in survival mode, Then, hold L2 when choosing that fighter at the character selection screen to play as the EX version. Note: This has no effect with Robo Ky, Kliff, or Justice. Alternately, complete the first two story mode paths for a fighter to unlock the corresponding EX character; or successfully complete 40 missions. Another way is to accumulate a total of 50 hours of game play. For every 2 hours of game play, one EX character will be unlocked. Note: To use an EX fighter in mission mode, successfully complete all 50 missions.
bob377 and Michael Bleser.

SP fighters:
Defeat an SP character in survival mode. Then, hold L1 when choosing that fighter at the character selection screen to play as the SP version. Alternately, complete all three story mode paths for a fighter to unlock the corresponding SP character; or successfully complete 40 missions. Note: For SP versions of Kliff, Justice, and Robo Ky, complete 50 missions. Another way is to accumulate over 60 hours of game play. For every 2 hours of game play over 60 hours, one SP character will be unlocked.
bob377 and Michael Bleser.

Mission Mode unlockables:
By completing Mission Mode a certain number of times, you can unlock various bonuses.
Wurd.

Secret Characters: Complete 40 missions.
EX Mode (all characters): Complete 40 missions.
SP Mode (all characters): Complete all 50 missions.

Fight as Robo Ky:
Defeat Robo Ky in level 210 of survival mode. Alternately, complete all 60 story mode paths, successfully complete 40 missions, or accumulate 96 hours in training mode and normal game play.
bob377.

Fight as Kliff:
Defeat Kliff in level 220 of survival mode. Alternately, complete all 60 story mode paths, successfully complete 40 missions, or accumulate 96 hours in training mode and normal game play.
bob377.

Fight as Justice:
Defeat Justice in level 230 of survival mode. Alternately, complete all 60 story mode paths, successfully complete 40 missions, or accumulate 96 hours in training mode and normal game play.
bob377.

Fight SP opponents:
Hold L1 when selecting either Arcade or M.O.M. mode.
bob377.

Fight EX opponents:
Hold L2 when selecting either Arcade or M.O.M. mode.
bob377.

Fight SP and EX opponents:
Hold L1 + L2 when selecting either Arcade or M.O.M. mode.
bob377.

Alternate costumes:
Press Square, Circle, Triangle, or R1 before pressing X to select your character. Note: Some characters' costumes do not change with Square.
G.B.

Restore original character colors:
In any of the modes except Story mode, press Square, X, Circle, Triangle at the character selection screen after choosing a character.

Justice Story mode:
Complete all 60 story mode paths to access Justice's story mode.
bob377.

Guilty Gear mode:
Complete all 60 story mode paths to unlock the "Guilty Gear Mode" option at the options screen. Alternately, accumulate over 58 hours of game play.
bob377.

Stage select:
Choose versus or training mode. Then, press R2 when selecting a fighter at the opponent selection screen.
bob377.

Boss stage select:
Select versus CPU, versus two player, or training mode. Highlight the ''Random'' character selection at the middle of the screen and press R2.
bob377.

Dialogue select:
Hold Punch, Kick, or Slash after the versus screen disappears but before the stage loads to select the dialogue set for your character.
bob377.

Alternate victory pose:
Hold Punch, Kick, or Slash after the victory message appears. Note: Not every character has a full set of alternate poses.
bob377.

Faster credits:
Hold Punch, Kick, or Slash while the credits are displayed.
bob377.

Slayer haiku:
Listen to Slayer's dialogue in the sound test screen and press Square.
bob377.

Hint: Easy kills:
This trick requires a programmable controller. Program the "Instant Kill" move for the desired character and assign it to L3. While in a match, press Square, Triangle, X, Circle to switch to instant kill mode. When you have just finished a combo, after they get up quickly press L3. If timed correctly, you should kill your enemy with ease.
GangstaT589.