Press Start during the game, and enter the following:

Full ammo: Circle, Circle, Triangle, Square, Square
Double ammo: Circle, Circle, X, Circle, Triangle
Unlimited battery: Circle, Square, Circle, Square, Triangle
Platinum gun: Circle, Square, Square, Circle, X
Improved battery: Circle, Square, Square, X, Circle
Slow motion driving: Circle, Square, Triangle, X, Triangle
Double damage: Circle, Triangle, Triangle, Square, Circle
Full battery: Circle, Triangle, Triangle, X, Circle
Cloak: Circle, Triangle, X , Triangle, Square
Golden gun: Circle, Triangle, X, Circle, Triangle
All weapons: Circle, Triangle, X, X, Circle
Unlimited ammo: Circle, X, Square, X, Circle
Easier movement in vehicle: Circle, X, X, Square, Triangle