Get Cheat Menu
Hold L, C-Right, C-Down, and the A button at the main menu.
Big Head mode
Enter BLAHBLAH at the cheat menu
Enter SHOWOFF at the cheat menu.
Turn all riders invisible
Enter INVISRIDER at the cheat menu.
Unlock Hill Climb
Finish 1st in the Gold Round of the Amateur Season.
Finish 1st in the Silver Round of the Novice Season.
Unlock NES Excitebike
Finish the Tutorial Mode by completing all the stunts.
Unlock 3D NES Excitebike
Finish 1st in the Challenge Round of Pro Season.
Type "MIDNIGHT" at the cheat code entry.
Enter YADAYADA as a code.
Small head mode
Enter PINHEAD as a code.