All of them. He would win against all of them. And none would last out of round 1, and less than 5 would probably make past 1 minute.
This might seem strange to someone who has never trained. But walk into a boxing gym, train for a week, then fight the club pro.. It'll be easy to understand there is no lucky shot you could ever land to beat him in the ring. Now imagine the same on a bjj mat.. How would you ever submit or even just survive against a black belt? You couldn't. But these are fair fights with rules, anyone with a gun in their hand has the potential to kill anyone in a split second.
But in competition, no untrained fighter would beat someone like you described.
above average skills and very experienced
I'm talking "very experienced" and assuming this means he's had more than a few mma fights and probably fighting at the pro level, above average skills for a pro fighter etc. is this what the OP meant?