Enter the following cheats in the Character Completion field, at the Cheats screen:
Password - Effect:
BIGDOGS - 500cc bikes.
BUSTBIG - Freestyle tracks.
CLAPPEDOUT - All bonuses unlocked.
ECONATION - National tracks.
MINIGAMES - Unlock all machines.
OBTGOFAST - Expert A.I.
SQUIRRELDOG - 50cc Bikes.
STUPERCROSS - Supercross tracks.
SWAPPIN - Pro Physics.
WRECKINGBALL - A.I. Bowling.