TheGameSite: Tips, Cheats, Walkthroughs: N64: Bust-A-Move 2
CHARACTER SELECT IN PUZZLE MODE
Start a Puzzle mode game. As you are getting ready to move the cursor to A or B (the first puzzle), on the Control Pad, press Left, Left, Up, Down, Left, Right, Left, Right, and then hold the L and R buttons. This will bring up a character select screen. Using your Control Stick/Pad, press Left or Right to highlight the character of your choice and then press the A button.
ANOTHER WORLD CODE
On the title screen, press the L Button, Up on the Control Pad, the R Button, then Down on the Control Pad. If done correctly, a little green dude will appear in the bottom-right corner of the Title Screen. When you go to the Puzzle Mode, notice Another World option below it. This new option is your ticket to a brand new world of puzzles!