At the main menu, select "Options", then choose the "Cheat Codes" selection. Alternately, pause the game, select "Settings", then choose the "Cheat Codes" selection. Then, enter one of the following codes to activate the corresponding cheat function:

Toggle Invincibility

Press Up, L, X, L.

Full ammunition

Press Down, Up, Down, Y.

Single player unlocked

Press Y, Down, R, Down.

Toggle location stat

Press X, Right, L, Left.

Win current match

Press L(3), Y.

Lose current match

Press L(3), A.