Ruliweb.com has released new SA2 screenshots. And apparently Tails is in it, Rouge and Shadow are playable, and there’s a two player mode. Have a look.
Sonic vs. Shadow
Tails vs. Eggman
Knuckles vs. Rouge (maybe Rouge is after the emeralds for jewelry!)
A better look at Rouge
Thanks to Zeefay for the tip.
Source: More Pictures can be found here.