Momotaro is shittiest theory to begin with.....Momo biting Kaido and making him scream itself is borderline acceptable given it stems from Kaido's own power.....but Momo killing Kaido is reaching or there are some comments that Momo will 'scar" Kaido with Oden's other sword....that is even more ridiculous......basically, it is just to spite ZKK (I am not ZKK group btw) .....
Yamato and Marco would then just lose, leaving it to Luffy. The initial Momotaro theories had nothing to do with anti-ZKK, it got spun into that garbage logic