Boss Select (Japanese ver. only):
To play as Testament, Justice, and Baiken without beating the game, press and hold Down, Square, L1, and R2 from the time after the PlayStation is turned on (white screen) to the Guilty Gear title screen. The bosses will appear above the normal characters on the character select screen.

Play as Baiken:
You must beat the normal mode using EITHER Sol or Ky.The slight trick is to get the 2nd player to join in while you are fighting someone, beat the 2nd player, and you then get to fight your match against the computer fresh. Getting the 2nd player to join in does not count as using a continue, so you basically get as many chances to beat someone as you need. But you must watch out for being destroyed, since this will force you to use a continue.

Play as Testament and Justice:
To fight as Testament and Justice, complete in arcade mode under the normal difficulty level. Continues may be used.

Hard mode:
Hold Down + Square + L1 + R2 and power on the PlayStation. Continue to hold the buttons until the phrase "Team Neo Blood" disappears. If you entered the code correctly, "Normal Mode" will be replaced with "Hard Mode" and "Hard" will appear above the two player/computer chaos bar

Alternate colors:
At the character selection screen, press Square, Triangle, Circle, or X.

Infinite Combo
Chip has an incredibly cheap, yet easy to do infinite combo - simply do his uppercut, then, right before the opponent lands, dash in, and do another one. Repeat.