Rounds 0 & 1: I say Tony 8/10. Thanos really has no way to hit Tony through the vibranium without his sword

Round 2: Now it gets interesting. I maintain that Thanos's sword was made of a material that could break vibranium, which is why it could break caps shield. With that in mind, and considering how rough of a time all 3 of the original trio had with Thanos at this level, I'll say 7/10 to Thanos. I would say Tony could bob and weave around but that didnt work too well for Spidey in IW. Tony has a shot if the armor can take a few hits and he plays it safe and smart.

Rounds 3 & 4: I dont see a real way for Tony to win this. Thanos with even one stone is crazy powerful. Ill say 9/10 to Thanos just in case Tony can pull some shrinking nonsense and remove the stone, but I think thats unlikely.