As I’m sure you have guessed Sonic Colors for the Wii has some secret unlockables in it and this guide will help you achieve them all.
Unlockable: Super Sonic
Collect all 180 Red Rings from the 36 acts to unlock the 2nd and 3rd Sonic Simulator acts. Now, beat 21 of these Sonic Simulator stages (you can do this in single player). After this you can select Super Sonic from the now-glowing Options Satellite on the Main Menu. Collect 50 rings to activate Super Sonic — some stages will change when you do so. You cannot use Super Sonic in Challenge Mode.
Unlockable: Playable Mii in Sonic Simulator
Collect 30 Red Rings to unlock a playable Mii in the Sonic Simulator.
Hint: Finish Line Minigame
At the end of each level you will see a screen with your stats for the level. you still have control of Sonic here, so jump into and dash through the numbers and you may score some rings and extra lives.
Unlockable: Rainbow Star (Credits Minigame)
Beat the game and watch the credits roll to make the Rainbow Star appear on your map screen. Choose it to play the credits minigame.
Hint: Change Sonics Color in Simulator
Go to the character selection screen in the Sonic Simulator and press Z or C (L and R for GameCube controller) to change color to blue, red, pink, black or green. -RonnoxAnnihilator
Easter Egg: title Screen Manipulation
At the title screen use the control stick to turn the camera to look at Sonic and the aliens from different angles.