Elite 260lb wrestler? Top 15 Middleweights could probably do it, maybe Hendrix or Lawler. Bout half the light heavies would be fine, some of the slower ones would get smothered and wouldn't be able to get off their back. And then I'd imagine, even without any striking or sub training, he could beat a few bottom of the barrel Heavyweights.
Welterweight and below, I don't think anyone could give him trouble on the feet besides Big Rigg and Lawler just because they wouldn't have the power or reach. but there may be a few guys who could pull of tricky subs.
Something like this from a 155er would actually work
I don't think brute strength would get him out of a thing like that. Like I said, it'd have to be sneaky. Not gonne force an arm back for a kimura or avoid getting rampage slammed on a triangle attempt from guard