Title Screen Cheat Codes
Hold UP+SELECT at the title screen and press B, B, A. Animation and sound will cease, letting you know that you've entered the code properly. Now you can press the A button repeatedly to jump to different levels, and you can press the B button once to enable invincibility or twice for unlimited lives and all items. This code does not work for the game's Japanese edition.
Cheat Code
At the title screen, hold Select+Up and press B, B, A. The title screen's music and animation will stop to confirm correct entry, and the following button cheats will now be available: Press A the amount of times corresponding to the desired level number (e.g. four times for level four) to start at that level. Press B for invulnerability. Press B twice for infinite lives and all items. Note that the code does not work in the Japanese version.