Sonic
This is kind of like unlocking Mewtwo. Play VS for 24 Hours. Then challenge Sonic. Beat him in Big Blue to unlock him.
A Button: Fast Punch
A Button + Up: FastUpward Kick
A Button + Down: Spin
A Button + Left or Right: Eagle Punch
A Button + Forward: Extreme Punch
A Button + Dash:Ultra Punch
A Button + Down + Jump:Downward Kick
A Button + Left or Right + Jump:Aerial Punch
A Button + Up + Jump:Upward Punch
B Button:Twister
B Button + Down:Tornado
B Button + Up:Upward Attack
B Button + Left or Right:Super Tornado