WarioWare Inc.: Mega Party Game$ Cheats

Play any mini-game:
Get a rose from all the mini-games in practice mode to unlock the final single player mode door. Use the final door to play any mini-game again.
User Cheat by Konga

Sound test:
Go through every multi-player mode to unlock the "Sound Test" selection at the options menu.

Bonus options:
Finish the games from the first door to unlock the "Character Descriptions", "Hard Mode", Mixed Genres Game", "Movies", and "Thrilling Mode" options.