Sonic Shuffle Cheats for Dreamcast
Play as Super Sonic -To unlock Super Sonic in versus mode purchase all pictures of Sonic in Sonic's room
Play as Chao - To unlock Chao in versus mode, get all pictures of Knuckles in Sonic's room
In story mode if you get 120 rings you'll be able to get a toy box in which you'll be able to play mini games with.
First go to the sonic room go to the pictures go to where it says another and buy picture 49.
Then you'll be able to play all the mini games that you've played in versus or in story.