It Was Never Meant To Bi

Rex won't stand by that bs

Yes. Always. Good lord. I never understand why people can turn this into a big serious discussion. Yes, One Punch Man would beat Thanos. He would beat Luke Skywalker, Superman, every single character from Dragon Ball Z, and every ninja from Naruto. He would beat Thor and Wolverine and the Hulk in a tag team match. 

Because he plays by different rules. One Punch Man is a PARODY character. His skill set is defined by comedy, not power levels or physical strength. One Punch Man not Superman facing off against an ever-more powerful lineup of villains. He’s the Roadrunner against Wil E. Coyote’s ever more convoluted plans. Deadpool is the only other super hero type character who comes close to living in the same realm of parody, but frankly, Deadpool repeatedly getting the crap beat out of him would be funnier than Deadpool winning, so One Punch Man would win that fight too, even if he can’t actually kill Deadpool in one punch. Because parody.

1) it’s conceivable that, due to the rules the other character is operating on (as in, whatever rules of comedy govern the other character’s universe), he might not be able to get in one punch.

AND

2) A compelling argument could be made as to whether it would be funnier for Saitama to lose that fight.

Canon example where both came into play: he lost the fight against that one mosquito, because it was tiny, fast, and flying, and because it was hilarious. Rule #1 alone isn’t enough, because if it isn’t funny for him to lose, he’ll find a way to punch through whatever restrictions are preventing him from punching the target.

So “could One Punch Man beat Superman/Thanos/Unicron/the Death Star?” will always go to OPM.

Remember when Roger slides out of his handcuff for a joke, then slides it back on and suddenly can’t escape because it wouldn’t be funny?

That sort of implies that it’s less a question of, “is saitama MORE POWERFUL than roger rabbit?” than it is, “Could saitama’s victory be FUNNIER than roger’s?”

At that point, the power is in the hands of whichever character would be the FUNNIEST to come out on top.

And in order to decide that, we would in turn have to decide:

“Which is funnier: a totally jacked man whose single dream in life is to find an opponent who could stand a chance against him finally, finally finding a worthy adversary in a goofy rabbit in a bowtie…