Dancing Stage MegaMix Cheats

All you need to do to unlock everything quickly is choose game mode, then single play... then hold triangle to go back to the main menu, and it thinks you've played 3 songs.

Repeat this as many times as you need to unlock all game modes and the 'MAX 300' hidden song.

(It's quicker if you turn off auto save but don't forget to save when you've unlocked all of the goodies).