Sonic Team’s SA2 page has info on some of the game’s bosses. Of course, the character vs. character battles are back, but the 2 other bosses mentioned are a surprise. Big Foot is a mechanical walker built by the military and one of Sonic’s bosses. It belongs to the “Scorpion Troop.” Shadow fights Hot Shot, a flying military machine that chases him and fires on the ground (which sounds like a very cool boss, IMO). It belongs to the “Spider Troop.” No clue what these “troops” are – maybe competing teams attempting to catch Shadow?