While I might argue that Martian Manhunter could take Supes in a fight (all that mind trickery and shapeshifting, man.) I do really like the Captain Marvel idea.

I was also considering going a completely different route; a character who's less punchy punchy. Like a Tony Stark or a Brainiac 5.

...I could also not do a comic book ch-nahhh. That'd be crazy.