.....and that's pretty much it. Shadow would be fine, but only if he dies in the end like was supposed to. Cream is adorable, but she has no reason to be there. I would not touch Trunks wannabe the Hedgehog with a 20 foot pole. the rest of the characters feel like filler to me.
He never really played a major role in the games, he was just a background character. He could have had a chance to shine (he was playable in Sonic Adventure for Dreamcast), but he fell by the wayside before he ever had that chance.
Well and there's that. Still even with a well coded game, if people can't get behind the character anymore, its a wasted effort. Just look at that new Rayman game. No one outside of Rayman's small, but die hard fan base gave a shit, and it didn't sell very well.
Why stop there? We could get rid of many of the single shot characters, and everyone from Sanic 2006. Except for Princess Whats-her-face. We need to keep her around in case the series needs terminated fast.
Princess Peach. And they did have Amy since Sonic CD (I suppose way more if you want to count the comics and the cartoons), but I suppose a token female is a bit cliche and unfair. Rouge is fun to play as though...as much as Knuckles since she didn't play too different in Adventure 2.