Imo, Zoro and Law proved they're >= YC level when they were taking down Vergo and Pica, which I consider YC level.
Kinemon is not going to shit his pants at a Tobi Roppo level guy. Usopp was trolling P1 and dude was fodder to Pica and even Trebol.
Although Zoro beating Kaido still ain't happening. Best thing would be take down King/Queen and hold Big Mom because Marco ain't doing shit for more than 30 seconds.