User blog comment:JustSomeDude.../761- Let's talk about Chapter 595!/@comment-24442815-20140919200836/@comment-24769684-20140920021513

All we know is that he's somewhere on or below Shanks' level, since before the Marineford Battle Shanks fought him and escaped unharmed.

Also, Kaido was trying to go after Whitebeard before the war, and I'm pretty sure he could fight on par with Whitebeard since he did this with such confidence.

Also, he has an army full of an indeterminate amount of Zoan users. Even if he's not as strong as people claim to be, he has this backing him up. And seeing the number of fruits Doffy's smile factory regularly makes, I'm betting it numbers in the 100's at least, most likely in the thousand's.