I guess I gotta spell it out for biased readers or people who are being intellectually dishonest.
Here is what we know for a fact about Kaido:
1- He likes playing around with his food which means he never goes all out on them from the start. Prove by how he fought the scabbards, proven by how he fought multiple versions of Luffy each stronger then the last.
2- Fighting this many people non stop drains stamina, holding and moving and entire island while fighting drains even more stamina. This is proven by the fact that momo who just tried moving Onigashima out of the way for a few second after Bajrang gun was exhausted. Kaido has been doing it for hours on end non stop fighting.
3- People like to downplay the gauntlet he went through because he fought people under his weight class, but
1- damage is cummulative,
2- we established he plays around and tests people so will take uneceassary damage,
3- His stamina isnt infinite and was slowly depleting through the fighters he was fighting and holding and moving the island.
4- When he finished his fight with Luffy pre G5 he was already nearing the end of his stamina limits as commented by Yamato herself. We know Awakened Zoans grant the user enhanced recovery and vitality. Luffys Mythical Zoan thus brought him back from the dead and was actively recovering him while they were fighting. At that point Kaido could barely even stand as proven when Luffy had to go through another round of G5, which funnily enough Kaido just stood there and watched him do it instead of killing him.
5- People like to use Kaidos top 5 to try and create their own headcanon of what they mean by saying that they were all stronger then him so why cant Shanks, ignoring completely the fact that he never said those 5 can defeat him, he said those 5 can fight him which mean he considered them peers to him. Now how can that be possible when one of the guys he considers a peer was his captain who died when Kaido was but an apprentice and far from his prime? For anyone with a modicum of reading comprehension and isnt a full time troll they would understand that Kaido was comparing those guys to his current prime self as thats the only thing that makes sense because of course apprentice Kaido who didnt even have his fucking fruit was no match for Rocks but the retards and insecure trolls here would like to ignore this fact and continue acting like buffoons.
In short: Yes, Kaido fought people under his weigh class, but thats by design, other top tiers wouldnt fuck around and mop up fast, he isnt not like them, he likes to play with his food this is canon fact, he likes to test people, he likes to take unecessary hits, he was draining his stamina for hours not only through those fights but carrying an entire island and moving it too which was commented on by his daughter Yamato. Those are all facts. When finally G5 Luffy happened the man was at the end of his ropes stamina wise and still performed extremely well we havent seen any top tier actually overpower G5 Luffy yet since Kaido.
So yeah for all of you retards who cant read or understand a manga for children, here is a quote from Oda:
Now you can all collectively line up and suck my dick.