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.
Tip:
When playing in Arcade mode at the normal difficulty level, the first
five opponents will (usually) be easily succeptible to being destroyed.
This gives the player an easy way to get past the first five opponents
without breaking much of a sweat.