Cinos the Anti-Sonic (Virgin Books)

History
When Sonic and Tails went back in time to undo their undoing of Kintobor's transformation, the version of Sonic from that point in time got caught in the ROCC's blast, turning him into an evil being filled with Chaos Energy. Cinos proved to be more than a match for Sonic and the two Tailses, whirling at high speeds, until his sneaker got caught on the floor and leaving him vulnerable. Using this opportunity, Tails found three gold rings to use on Cinos, believing they could "neutralize his energy" as Sonic put it. It did not work so well, so Sonic touched Cinos instead and slowly absorbed him, as he was his temporal duplicate.

Appearance
Cinos had white fur. His expressions appeared to be those of complete evil, as shown when he and Sonic merged.

Powers and abilities
Cinos was every bit as speedy as the real Sonic. His body was also apparently filled with Chaos Energy.

Weakness
Cinos' Chaos Energy-infused body proved to be his downfall, as rings can be used to neutralize his energy.

Background Information

 * Cinos's name is "Sonic" spelled backwards, reflecting how Cinos is a evil counterpart of Sonic.