None of those were an actual fight but cheap shot fest that Marineford was. When forced into a 1vs1 against Rayleigh, we saw how he fights, as a swordsman who ended up pissed because he couldn't catch the Supernovas. He was at his best with a sword.
Roger, Kaido, Vergo, Blackbeard, Doffy are not at their best with guns.
Zoro can perform Oni Giri with a scythe. What is your point?
As if Fire and Thunder can do anything to Kaido while a sword indeed can. Try again.