My guess is Luffy will use 2 King Kong Guns.
1st time he will fail to use CoC properly but KO Kaido for a bit before he uses awakening. That will drop Onigashima before it hits the Flower Capital.
2nd time they will fight on Wano and he'll use KKG properly, where Straw Hats will all stall for 10 minutes, and he'll use KKG with advanced CoC properly to KO him for good.