If it turns out he does get a simple palette-swap based super like Arthur, I'd imagine he'd basically be invincible and stronger for a short period of time (or have super armor that lasts until it's gone)
There is a listing of abilities from various other source games on the site below.
http://sonic.wikia.com/wiki/Super_Sonic Projectile reflection is an interesting consideration.
Also wanted to suggest another move, being Sonic's lightspeed attack from SA1 and 2, would be probably fairly easy to implement since all it would use is his rolling sprites.
It may also work to implement an effect similar to that of the last few Sonic games for a stomp/slide move as shown below.