If we powerscale Luffy asspulls it's
Major: Gear 2,3 (seemingly invented theoretically before busting them out)
Normal: Soru, CoC attacks (grasped after it's used by others and had the abilities required to use them)
Minor: Gear 4 (previous gears no longer taxed Luffy and coming up with something new in 2 years is reasonable)
Given that Kaido seemingly doesn't use/know AdvCoA considering how he reacted earlier in the fight I'm also presenting the superficial theory that Luffy's CoC attacks are enabled/strengthened by his knowledge of AdvCoA in a similar way that his Soru technique was enabled/strengthened by the use of Gear 2.
Major: Gear 2,3 (seemingly invented theoretically before busting them out)
Normal: Soru, CoC attacks (grasped after it's used by others and had the abilities required to use them)
Minor: Gear 4 (previous gears no longer taxed Luffy and coming up with something new in 2 years is reasonable)
Given that Kaido seemingly doesn't use/know AdvCoA considering how he reacted earlier in the fight I'm also presenting the superficial theory that Luffy's CoC attacks are enabled/strengthened by his knowledge of AdvCoA in a similar way that his Soru technique was enabled/strengthened by the use of Gear 2.