I would get my butt kicked hands down.
Probably most everybody on here, that isn't a decent level MMA caegfighter, would probably get smashed up just the same.
People need to look up sumo. See how these guys train?! They aren't just piles of lard, they are living breathing tanks! Geez, these guys train nonstop in tough conditions.
I couldn't imagine the strenght and power of these guys in real life. I saw one Sumo guy, who was from Europe (European not even Japanese!), 40 something, in his first pro MMA fight beat James McSweeny who fought in the semifinals in one of the recent Ultimate Fighters. The Sumo guy charged him, took him down, put his massive weight on him, and won......by a smother! His blubber smothered the guy and made him tap! These guys aren't to be screwed with!
They are not the ultimate fighters around mind you. But, for the average guy? You would be a sumo wrestlers' appetizer before a real challenge, maybe if that.