One Piece: Is Luffy strong enough to beat an Emperor?

That depends on the situation. We have seen Luffy losing at first and winning right after due to certain circumstances, either by power ups or by pure luck and experience.

One clear example is when he fights Crocodile in Alabasta, a place where Crocodile reigns supreme because of the terrain advantage. He losses twice, even came close to dying if not for Robin that came to save him. But the winning factor in this situation is not just brute strength, it was his observation and luck. Luffy noticed in their previous fight that Crocodile’s weakness is water. And his luck kept him alive as Crocodile is an arrogant prick who thinks too highly of himself and underestimated Luffy durability.

In case of winning by power ups, we have seen it in the Water 7 arc. Utterly defeated before, but gaining massive power ups after that leads to winning after.

Both of these situation although decided by different factors, it shares the same key factor that leads to all of his win. It is Luffy’s MOTIVATION! It is what drives him the most, affected his willpower to survive and to win. And it always for saving someone close to him.

Now back to the main question, does Luffy has what it takes to beat an emperor? To be able to answer that we must know the strength of the emperor. So far we have only seen the powers of 2 emperors, Blackbeard and Big Mom. Blackbeard is most definitely stronger now since we only saw his power from 2 years back. Even with Luffy’s current strength, compared to Blackbeard then, Blackbeard could easily decimated him. 2 devil fruits? Insane durability? Yeah, no chance at all, for now.

So how about Big Mom? Does Luffy has a chance? Personally I think he does. Big Mom has 4 significant powers, her devil fruit ability the Soup Soul fruit and her 2 original homies, Prometheus that provides fire and Zeus that provides lightning and the last one, Conqueror’s Haki. The Soul Soul fruit relies on people being afraid of her to take effect, we can see that it failed to affected somebody who doesn’t afraid of her like Jinbei which surprises Big Mom herself. Seeing Luffy openly challenging her, even going as far as doing the stunt with the wedding cake, clearly shows Luffy isn’t afraid of her at all, so Big Mom couldn’t be able to steal his life span. We all know Luffy is immune to lightning as he is rubber so that leaves Zeus as a threat. Prometheus might give him trouble as Luffy isn’t immune to fire, but the speed of attack isn’t something that Luffy couldn’t avoid. Last one, Big Mom’s Haki. Recent chapters has shown that Luffy could even compete with Big Mom’s haki, signalling that his willpower is at emperor’s level already.