Pause the game and input the cheats to activate the codes.

Hold L and press Up, Up, Down, Down, Left, Right, Left, Right, X, Circle - All Weapon Upgrades.

Hold L and press Up, Up, Down, Down, Left, Left, Right, Right, Square, Triangle - Invincibility

Hold L and press Triangle, Triangle, X, X, Square, Circle, Square Circle, Down, Right - Refill Ammunition

Hold L and press Triangle, Triangle, X, X, Square, Circle, Square Circle, Right, Down - Unlimited Ammunition