Choose the "Options" selection at the main menu, then press L1 or R1 to cycle from the "Game Settings" option until the "Cheats" option appears. Then, press Down until the desired cheat option appears. Press Circle to display a keyboard that is used to enter the code to unlock that cheat option.
Enter "CLAPPEDOUT" as a code for the "Character Completion" option at the "Cheats" screen. All bonuses in the game will now be unlocked.50cc and 500cc Classes
Enter "SQUIRRELDOG" as a code for the "50 cc Class" option at the "Cheats" screen.Pro Physics
Enter "SWAPPIN" as a code for the "Pro Physics" option at the "Cheats" screen.