Dr. Julian Robotnik (Jim Cummings) betrayed the king of Mobotropolis and turned it into the dystopian Robotropolis.
The nephew of Robotnik, Snively (Charlie Adler), he's the doctor's henchman and much like Scratch and Grounder drew the villain's ire when plans failed. He secretly grew to resent the Doctor and made plans to usurp him.
Robotnik's pet ,Cluck, he was essentially the evil pet that all cartoon villains we're contractually obligated to have back then.
Swat Bots were the invention that put Robotnik in the king's favor originally, and they are what he would use to spell the kingdom's downfall. Cold and threatening, these machines we're much more of a visual threat than the goons from AoStH.
Ixis Naugus (Michael Bell), a powerful sorcerer who Robotnik trapped in another dimension and would've been the main villain in the scrapped season 3.