Well, that was certantly.....original.
Despite its corny movements and strangeness, I found this flash to be pretty entertaining! A couple things for you to note, however:
1) Although the transistion was smooth, it looked wierd having [Sonic Advance] Sonic morph into [Sonic 3] Sonic and then into what looked like [Sonic Crackers] Sonic. I understand that the transitions were quite essential, however I found them rather strange and annoying.
2) Dr. Ivo "Eggman" Robotnik was actually in two places at once. He was in his hover car and dancing on the ground at the same time. Kinda wierd...
Anyway, an original idea and a pretty good flash overall. Good job!