Cheat mode
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.