I understand that the overall meaning is "the titular superhero has been overshadowed by the myriad of powerful villains he has fought against," but I don't see the purpose off adding that "所衬托的," and trying to translate that/see its function here in the sentence is driving me crazy.
I know that the meaning of 衬托 is to set off or serve as a foil to. This makes me think that it serves to modify the "fought against" or "对抗" part of the sentence, but I just am not sure, and do not know how to integrate 衬托 into the English translation specifically.