I kinda feel like unless you literally just dumped thousands of bodies on him to technically win a ten-count, there's really nothing they're gunna reasonably be able to do to him, even ignoring the idea that they probably wouldn't even realize he's there at all.

I guess TV Swamp Thing, you could dogpile a few dozen zombies on him to pin him down. If this is in the Khazan Arena, I guess old Swampy doesn't actually have any plants or animals to manipulate to help him out. I dunno if they can actually hurt him, though.