To get all the power-ups, pause the game then press Up, Up, Down, Down, L1, R1, L1, R1, X, Circle. You should hear a *ding* to let you know the code worked.
Disable All Power-Ups
To disable the All Power-ups code, pause the game then press Up, Up, Down, Down, Left, Right, Left, Right, X, Circle. When you unpause the game your character will be surrounded by the words "Oh! My God" briefly indicating the code worked.