Level Skip
Press y, y, x, x, left trigger, right trigger, down, down, up, up on the pause screen.
Extra Lives
Press a, b, x, y, left trigger, right trigger, up, down, left, right on the pause screen.
Extra Credits
Press a, b, left, a, b, right, b, a, down, right trigger on the pause screen.
Level select
Pause the game and press Up, Down, Up, Down, Up, Down, Left, Right(2), Y.
Grenades
Pause the game and press Down(5), Up(4), R.
Shields
Pause the game and press Up, Down, Left, Right, X, Up, Down, Left, Right, Y.
Instant victory
Pause the game and press L, R, L, R, Left, Right, Left, Right, Y, X.
First person view
Pause the game and press L, Left, R, Right, X(2), Down(2), R, L.
God mode
Pause the game and press Up, Down, Left, Right, L, R, Left, Right, Start.