Woohoo I finally have one of these. I tried to make one last year out of model magic and failed.
He is made with a modern Sonic's head, a classic Sonic's body, marvel legends mojo legs for the arms and legs, with a wire tail. The rest of the sculpting is done with green stuff. I like the way he turned out, I just wish I knew how to make it so that the limbs would still articulate. Oh well.