Oh, I see, I expected that you'd at least go through my other posts, where I explained my reasons to the other guys who originally quoted me, before accusing me of wanking. Whatever, no hard feelings. I'll give you my reasons:
Kaido mocked the Scabbards that a combined attack from four of them is too shallow:
Meaning Togen Totsuka did an insignificant amount of damage. If even a combined attack from 4 people did only insignificant damage then there is little chance that they did anything noteworthy when they attacked individually. I am not saying the damage Scabbards inflicted is irrelevant but still insignificant.
Killer, Yamato, and Kid did barely anything better than the stronger section of the Scabbards—i.e., Kawamatsu, Inu, and Neko. Law did something noteworthy at least.
Luffy, before COC, potentially did more damage than all the Scabbards combined, it was still too shallow by Luffy's own admission:
After that, Luffy punched Kaido twice with COC attacks. I doubt they did anything noteworthy, but they still count.
Meanwhile, Zoro's Tatsumaki was the first-ever attack that made him vocally express that it hurt him:
Meaning he did some damage worthy of acknowledging although it's still insignificant.
With Asura though, Kaido was visibly distressed which is evident from him expressing his agony by saying "damnit" while looking at the wound holding it which puts a special emphasis on the damage done and implies that it's significant.
Even when Zoro was disappointed that he did not knock him down, Kaido assures him—notice how he's shivering while saying it—that he did enough damage, once again, implying the damage inflicted is significant.
Also, Kaido started huffing, even while talking, after Asura:
All in all, it's bluntly obvious Kaido suffered the most damage from Asura although the others also definitely played a role regardless of however small it is.