There’s really not. Law and Kid are fighting someone who is on Kaido’s level, have pushed her so far that she actively cut out a year of her lifespan just to fight them. Meanwhile, that same person would utterly destroy King, who Zoro is fighting, who Zoro was also getting overwhelmed by. He’s not close to them. They’re Luffy’s rivals. They’re not going to be his equals, but they’re going to be close as hell, particularly in my opinion Law (I believe he is or will be the Whitebeard to Luffy’s Roger).
Big Mom was referred to as “the iron balloon” or something of the like when he was talking about the Yonko. She hasn’t taken damage in decades, except, according to Bege, one time she went through hunger pangs and cut her knee. Kaido meanwhile has been defeated seven times iirc, and when Luffy hit him in chapter 1000, recalled a group of people that he associated Luffy with (as people that he takes seriously), one of whom was Shanks. Shanks was the youngest of that group, meaning Kaido would have encountered him much more recently, meaning he probably would have taken damage much more recently than what was said about Big Mom.