As one of the Yonko, Kaido is among the 4 strongest pirates alive. He’s renowned as the “Strongest Creature in the World”.
Notably, Kaido has a bounty of 4,611,100,000 Berries, which is the highest of any pirate currently alive, surpassed only by the bounties of the late Whitebeard and Gol D. Roger.
Kaido attempted to take Whitebeard’s life, something few would dare, and subsequently clashed with Shanks. When Gecko Moria was in his prime, Kaido fought him and emerged victorious, having killed his entire crew.
He also defeated a prominent member of the Worst Generation, Eustass Kid, whose bounty is 470,000,000 Berries, with apparent ease.
Kaido has a very strong will, as shown when he was completely unaffected by Luffy’s Haoshoku Haki. He also possesses nigh indestructible durability, even without using Busoshoku Haki.
Kaido also clashed with Big Mom continuously for one to three days, and emerged without any injuries.
While the Red Scabbards were able to accomplish the rare feat of drawing blood from him with their swords and attacks, these wounds were shown to have very little effect on him.
He could withstand having his immensely destructive Bolo Breath redirected at him by Raizo’s Maki Maki no Mi, as well as assaults from Nekomamushi amd Inuarashi’s Sulong enhanced attacks, Kawamatsu’s Amano-gawa, Izo’s Dangirigan, and Kikunojo’s Zansetsu-gama, ultimately requiring Kinemon, Denjiro, Inuarashi, and Ashura to focus and coordinate their Togen Totsuka attacks together at his scar to finally inflict significant damage. However, Kaido himself stated that the injuries were still shallow in comparison to when Oden inflicted him with a massive scar.