Even ReSaurus had prototype figures. These early shots of their Knuckles and Giant Talking Sonic figure show different paint jobs, which, fortunately for everyone were fixed before release. Knuckles has awful near-sideways goat eyes (What IS IT WITH THAT? Similar awful mistakes keep getting made down through the years with ToyIsland Super Posers being the latest example) The Sonic has his eye down in his...lower face part-way as well as being somewhat tilted which also makes him look bad. You can see how these really turned out on the regular ReSaurus figure pages. These photos will remain here forever as the figures were never produced this way, and the company is out of business. 

Prototype Note Only: Eggman was planned to be released on one of their lines. Their 3rd line was to contain Super Sonic and also Rouge the Bat, but they went out of business before anything was ever produced.

*Interesting prototype art link for ReSaurus is Resident Lilly. This artist seems to have worked with ReSaurus trying to make the Eggman figure & other production sketches. They went out of business, but the artist apparently got to keep their own work on it & has hosted it at DeviantArt if this is actually the real deal.