Insant Kill Meter Fill
At any time during a fight, simultaneoustly press L1 + L2 + R1 + R2 + Square + X + Select.
Play as Cain, Judas and Marukka
Beat the game on the medium difficulty level.
Alternate costumes
Complete all of a character's moves in practice mode. Then at the character selection screen, highlight a fighter and press L1 + L2.