Cheat mode
Press [Left]x5, [Up]x5, [Right]x5, [Down]x5, [Select]x5 at the title screen. All levels and bonuses will be unlocked. To access the sound test, hold [A] and press [Left] or [Right] to make a selection, then press [Select] to hear it. Select the "Scrapbook" option to view background information about the game.
View ending sequence
Enter "staff" as a case-sensitive name. Enter the snack shop to view the ending sequence. Note: This also unlocks the hidden credits level. Quickly jump twice to get on top of the low building that appears immediately before the programmer's credit. Then, jump up and keep jumping to the right on the clouds until you find a hidden message.
400 medals
Enter "xyzzy" as a case-sensitive name. Then, hold [A] and press [Select] to increase the medal count to 400. Hold [A] and press [Select] again to reset the count to 0.