Dogtooth handicapped himself because his sister aided him in that 1 v 1 fight. If it wasn't for her, Luffy would've dodged that Mochi thrust, that's why he skewered himself because it wasn't an earned attack.But Kata heavily handicapped himself not to mention he was never going for Luffy's throat and no Luffy didn't beat Kata 1v1 and forget about Kata I meant Cracker or did you purposefully forget that figh because it defeats your point? also like chopstick said 4th gear didn't even scratch Big Mom
Other than that he did 1 v 1 Dogtooth in an all out war but he did need help to defeat Cracker. Cracker was the kind of opponent that would have trouble against Mizu Luffy.
Personally I feel like Luffy will gain some type of strength that will help against Kaido, possibly he will awaken to save stamina or heighten his recovery ability. Right now Luffy's on the same level as Teech was one-year ago when he defeated Marco. I think the people that is coming after Kaido including minks w/Marco will give Kaido some problems