Their line-ups are: Hero; Sonic, Tails, Knuckles. Rose; Amy Rose, Big the Cat, Cream. Dark; Shadow, Rouge, a beefed up E-102. Chaotix: Vector, Charmy, Espo
Seems as though Shadow isn't dead. he's in this and Sonic Battles for the GBA which i've also added. Apparently each team utilizes each character's skills someway. Hero has tail's flying, Sonic's Speed and Knuckle's strength. Also each team has signature moves. I hope there will be four player action because that looks like it would be fun. Also levels look arcadey and not too serious which was partly sonic Adventure's downfall because it was trying to be both.
http://www.sonic-cult.org/upcoming/Sonic_Heroes/