now that I think about it....
doesnt Who's Who remind you of Daz Bones, the same type of attitude not listening to anyone but Kaido and also was very popular in west blue, which I think similar thing might be for Who'sWho once being a BigShot Pirate (he even considers killing Queen and is happy he can fight Calamities), I wouldnt be surprised if Who's Who had around 1Billion Bounty (would make him the only Non Yonko related Pirate "beside Mihawk" who has had that much bounty "Luffy is Considered 5th Yonko now")
and also there is another similarity in this arc and that is Luffy getting beaten twice and succeeding in 3rd like alabasta overwhelming opponent and Kaido already defeated him once and one more is coming as we all know its likely
doesnt Who's Who remind you of Daz Bones, the same type of attitude not listening to anyone but Kaido and also was very popular in west blue, which I think similar thing might be for Who'sWho once being a BigShot Pirate (he even considers killing Queen and is happy he can fight Calamities), I wouldnt be surprised if Who's Who had around 1Billion Bounty (would make him the only Non Yonko related Pirate "beside Mihawk" who has had that much bounty "Luffy is Considered 5th Yonko now")
and also there is another similarity in this arc and that is Luffy getting beaten twice and succeeding in 3rd like alabasta overwhelming opponent and Kaido already defeated him once and one more is coming as we all know its likely