First off, Wargreymon is a Mega. There's a couple others who trump him (or equal him) in power, but they are rare (notably, a few from the movie).
He would own this fight. Colossus is, unfortunately, out of his league. Most Mega's probably bridge the gap between Earth-brawlers like Colossus and more cosmic people. I can't see WGmon taking on, say, even a minor herald....but they're close.
3rd, Digimon still rules. Don't be ashamed if you watched it (even though it's not allowed here).
