Cheats:

B&W Ardy Die holding L + A.

Old Style Ardy Die holding L + B.

Introductory Level Skip Press Start + Right + Y

Invincibility and High Jump Hold Right, Y, L and A. Then press start. During the game, press L to become invencible and R to jump higher.

Miniature Ardy Put the cursor in Game Start in the Presentation Screen, then press Up + X + Start in this order.