Ironman in his standard armor (No Hulk or Thor Buster)
Vs.
Megaman, with the full compliment of weapons upgrades he's gained from Megaman 1 through Megaman X 8, and his trusty robo-dog, Rush (and all of his sobsequent upgrades).
Iorn man could beat MM. MM's shown little to compare to the nuclar powered ball of ass kicking IM is.
X with all his power ups might win, his bigest disadvantage is lack of flight, but other then that he proboly has more firepower then Tony has acess to in his normal armor.
Megaman with access to ALL those little upgrades he gets in the games? Jeez. I think I agree with whoever said Megaman could solo this. It wouldn't be a walk through the park, but that's just too much versatility.
Megaman X, with all weapons upgrades available to him, as well as the weapons available to Megaman from the original series ("Megaman Prime"). Everything from Cutsman & Gutsman up through the Sigma battles.
I added Rush so Megaman would have flight abilities, among other things.