Probably could one shot Oden with a KKG, sure. Difference is, Kaido’s Divine Thunder/ club swing is not even the pinnacle of his offense while KKG is for Luffy. So Kaido’s offense should still be superior imo. The whole reason for Luffy’s training was for him to get by his durability, not surpass his offense....which is still impressive from what we have seen so far (in base anyways) even though his durability is highlighted.