Amy
After the level Sky Chase , play as Sonic and talk to Amy the casino.
Big
Play as Sonic and beat Chaos 6.
E -102 Gamma
Play as Sonic or Tails and beat Gamma after finishing on level Sky Deck. You can also unlock it by completing level Twinkle Park by playing Amy.
Knuckles
Defeat him after finishing Ice Cap playing as Sonic or Tails .
Details
Complete Mission C Emerald Coast by playing Sonic.
Super Sonic
Complete the game playing as Sonic , Tails , Knuckles , Amy , Big and E -102 Gamma. Super Sonic will be available only in the Adventure mode.
