Play as Cain, Judas, or Marukka
Beat the game on the medium difficulty level.
Complete all of a character's moves in practice mode. Then at the character selection screen, highlight a fighter and press L1 + L2.
Instant Kill Meter fill
During a fight, press L1 + L2 + R1 + R2 + Punch 1 + Kick 1 + Select.