People keep talking about the momotaro legend as to why Luffy Marco and Yamato with momo will figrh kaido.
However I disagree that oda is following the momotaro route in reference to kaido. He has already explained that legend.
The legend that oda is probably writing in reference to defeating kaido is the legend of the nue that fought the dragon.
The Nue (鵺, 鵼, 恠鳥, or 奴延鳥) is a legendary yōkai or mononoke (lol momonuske)
The nue has the head of the monkey (luffy)
The body of the dog (Yamato)
Legs of the tiger (Zoro)
Tail of the snake (hmmm I guess boa?????) No clue. Unless they are substitutjng Momo's dragon form as the snake. Which also is japanese mythology the snake becoming dragon