Only steve from minecraft can defeat him let me explain Steve can in his hand hold a stack of gold blocks in his hand. That’s 64 cubic metres of gold. The weight of one cubic meter is 19 320 kilograms. Toghether it’s 1236480 kilograms of gold. Let’s say that’s his punching force. An average Karate blackbelt punches with the force of 325 pounds. In pounds, steve’s punching force is 2725971,7795 pounds. That over 8000 times as much as the average blackbelts punch force.
The Average force needed to break a human bone is 4000 newton. Steve’s punch is 12.125.729 newton strong. That’s over 3000 times as much force as neccessary. Even if Thanos’ bones are 100 times stronger than the ones of the avergae human, Steve can break his.
What about Thanos hitting him? Steve can withstand all that force himself, as fists in pvp do next to nothing. Thanos can not do anything.
So to conclude, the outcome of this battle is determined by whether Thanos has the infinity stones or not. If he does he wins, if he doesn’t he loses.