Luffy has yet to defeat Kaido in "One Piece" as only a Yanko is said to bring down their kind. There are theories that after Big Mom and the Beast Pirates general face each other, Luffy and Eustass Kid will finish them off.
No one has defeated a Yonko, aside from Whitebeard and World Government's fight in "One Piece." Marshall D. Teach managed to crush Whitebeard down, but he had a hard time to kill him even though he was "very old and sick."
So, according to OP Fanpage, it might mean that the only person that could defeat a Yonko is another Yonko. It could also mean that the one who could bring Kaido down is his kind. As Big Mom is now on her way to Wano Country, is she the one to kill the beast in "One Piece?"
Business Times previously reported that Big Mom and Kaido might fight each other to get Luffy's custody in "One Piece." So, fans won't see a battle between Straw Hat Pirates, Big Mom Pirates, and Beast Pirates, but Big Mom and Kaido on war instead.
Big Mom and Kaido's clash can mean the Wano Country's end, but it can be avoided if Luffy and his allies can bring the male Yonko down. But how will he do it? The fan page continued to predict that Big Mom and Kaido are either going to kill each other or weaken one another until Luffy and the Alliance can finish them off in "One Piece."
In "One Piece," Luffy is the strongest person in the Alliance, but he is not strong enough to defeat Kaido. He got even knocked out with one hit. He still needs to gain more strength, so there is the prisoner mine.
The mine serves as Luffy's training that will eventually make him stronger by lifting huge and heavy stones and running to move it to transport ships. If he is not in training, he doesn't do anything but to eat and sleep while wearing handcuffs.
Eustass Kid, on the other hand, undergoes the same training so that he may become as strong as Luffy. With the strength they have, there is a strong possibility that these two will work together to defeat Kaido in "One Piece."
However, there are "One Piece" theories that Luffy and Kaido will not go on a battle until Wano Arc's final fight. But the Greater Calamities, Queen, and King will reveal their powers, so the Straw Hat Pirates and their allies should be powerful enough to be in a big fight.
