The team includes Johnny Lightfoot (rabbit), Tux (penguin), Princess Acorn (presumably a squirrel, but she doesn't look like it), Sonic, Joe Sushi (walrus), Chirps (chicken), Porker Lewis (pig), and Flicky (bird). Tails isn't pictured, which suggests that this concept art might have been made before Sonic 2 was released.
These characters are obviously based on the animals that Sonic rescues in his first game. Even their names are the same as the ones that Sega of America and Sega of Europe used for the animals (except that the squirrel was called Sally Acorn, not Princess Acorn or Princess Sally).
It's probably a safe assumption that Sally, Bunnie, and Rotor developed from Princess Acorn, Johnny Lightfoot, and Joe Sushi. Well, maybe developed is the wrong word. These guys are like the antitheses of their SatAM counterparts. It's as if someone told the SatAM staff to turn them into their polar opposites. Similarly, this Porker Lewis is nothing like the version in Fleetway's Sonic the Comic.