Alright well, after thinking about it, master chief stands no chance against iron man....sadly his badassness just can't cut it. So I think the problem lies in not enough badassness. Now Tony has to fight all the spartans that were made ...there's probably like 20 or so (don't worry about the 117),With all their weapons and this time vehicles. Is this more badass than Tony can handle?
I say Spartans 'cause they're cooler. (Hey, I've heard worse arguements...)
Are they spartans with energy swords? Those things can cut through anything.
True, but he's gotta run out of fuel or overheat his boot jets eventually. Plus he'll have to dodge 20 spartans shooting at him with tanks, chain guns, rockets, grenades...etc. If they dont wear down the armor, all that ordnance should still knock his ass out of the sky.
^ Cortana: Could we possibly make anymore noise? *Master Chief pulls out rocket launcher.* ...I guess so.
When Ironman's shields are down someone could just weapons bash him from behind, or skewer him with the energy sword.
How about sticky blue grenades? Can he shakes those off while flying?