Avengers Big 3, Fantastic Four and X-Men (Cyclops, Wolverine, Professor X and Iceman (omega level)
Masters of Evil (Ultron, MODOK, Enchantress, Executioner, Absorbing Man, Wrecker and Crimson Dynamo)
They are superior in almost all categories. The only problem could be the Living Tin Can but either Thor or Reed with the help of Susan can bring him down.
Susan can simply put her force field inside Ultron's body and freeze his circuits (Reed will tell her to go for that tactics).
It is even possible that Johnny with his flame could also fry the interior of Ultron (but this is less believable)