He didn’t push Kaido on the rooftop though. He pushed Big Mom with his awakening that’s it. Nobody on the rooftop pushed Kaido except Luffy.
Kaido literally called them all monsters on the rooftop. And law and Kid even before awakening were giving big mom troubles.
The warlords are able to fight with emperors. Doffy who was a good bit stronger than rooftop law would absolutely do more against Kaido than Yamato did for example.
Crocodile has an insane amount of hype canon and even in stampede oda added in that prime Croc is as strong as Prime Rayleigh.
Mihawk is self explanatory
Blackbeard himself feared Boas powers and we both know those powers would likely work on Kaido as well.
The seraphim are replacing these monsters. Of course they’re able to hold their own against an emperor.