Master Code:
Hold L1 then press Right, Left, Up, Down, L2, L2, R2, R2 at main menu. Then, press Start during game play and activiate any option at the cheat menu.

Unlimited Ammunition:
Press Down, Right, Up, Left, L2, L1, R2, R1 at the main menu. Then press start during game play and activate that option at the cheat menu.

Unlimited Life:
Press Left, Left, Left, Right, L2, L1, R2, R1 at the main menu. Then, press start during game play and activate that option at the cheat menu.

Thanks to Revolution reader Matt C.!