Now to analyze highest AP Roronoa Zoro's attack.
Kid, Killer and Law didn't do real damage to Kaido because they never could bypass his durability so their damage dealt is 0 or close 0.
For Luffy, his red Rock did minimal damage (slight bleeding), his Kong Gun and Schneider did no damage. His Kong gattling from this chapter actually did real damage with Kaido coughing up blood.
For Zoro, his Oni giri did 0 damage. His tatsumaki did real damage because not only did he cut through Kaido's durability and made him bleed, he also made Kaido cough up blood and Luffy.
It is logical to conclude that Luffy's did more damage because his attack was high level with 20 or so punches maxing out his haki. However, Zoro's attack did close to that damage with an attack which wasn't even high-level and was singular tech. Confirming again that Zoro holds the highest AP(Potency)