Pause the game, hold L1 + R2 and press Up, Triangle, Down, X, Left, Square, Right, Circle. Release L1 + R2 and press L1, R1, L2, R2. Wait a moment, then press Start followed by L2 + R2. Then, a debug menu that allows invincibility, secret weapons, enemy summoning, toggle enemy AI, FMV sequence skip, and other effects will appear.