You're not the only one who would like to see some Sonic related models/skins on this site. (That would actually be a good idea) I have a friend whos working on a Sonic themed action RPG hybrid map. It's about 97% complete, but it needs some custom models (doesn't have to be high poly as long as they are good, and some things are being reworked) to be really cool. I don't think Rouge requires a custom model, most likely just a recolorized Demoness skin.
I am one of THE biggest fans of sonic and shadow. I even have a hedgehog named sonic. (I'm a bigger fan of shadow- as you can see by my avatar- but my dad wouldn't let me name it shadow- said it was evil or something) Anyway if I could skjin or model I would sooooooooo help you! I think that attack animation should be them going into a ball and ramming into the enemy.
What exctly would a Sonic skin fit onto...? The closest thing I saw was a Spiderman skin on a Ghoul, which looked suprisingly good considering the odd shape, but I don't think there are any models that would look good with a sonic skin...