I'd personally want the Classic trio, Sonic, Tails, Knuckles, then Shadow and Amy. And then have Eggman, Metal Sonic, and Mecha Sonic as the antagonists. I kinda wish there existed a Metal Tails. It'd be way better than the Tails Doll, but I digress. I'd would also like it if Shadow was evil again, because it would then balance out the number of good guys and bad guys, plus he would be a dastardly villain and would always have epic battles with Sonic.
Silver and Blaze shouldn't really be in SA3 because they deserve to be in their own timeline. A spin-off for them would be nice.
sonic and shadow - high speed action with springs, 3d loops like in green forest, not dash marks, they make sonic and shadow look slow
Knuckle and rouge- find emeralds on the way to the finish, like sonic and shadow levels, but with emeralds
tails and eggman/robotnik- this is what it all comesdown to , tails could have his red blaster thingy, and u have to reach the end, he can still fly and all that, itll sorta be like samus with a jet pack , now robotnik, he could have his flying thing from sonic one, with the wreking ball to
I think, in SA3 from game characters should be Sonic, Tails, Knuckles. Plus in a multiplayer should be added Amy, Metallix, Eggman, Chaos. To me certainly like Silver and Blaze, but I think them in SA3 to add it is not necessary. I think the main villain in game should be Eggman. I'm Sonic Fan from Russia. My name Dmitriy Rybnikov.
the formula for the sonic adventure games, (idleast i think) is Sonic, tails, knuckles, 1 familiar character (amy, Robotnik) i think it would be cool as cream, and 2 new characters. (that should change in sa3.) maybe put shadow and e-102 beta