What form he used doesn't change anything, Luffy fought with kaido after fighting Ulti and greatly increased the power of all his forms, so G4 after the rooftop battle is something completely different, and the argument you used "kizaru beat Luffy with a single attack on gear 4" is wrong, we saw that He couldn't do that with his attack on Sanji, what I would look at is not what he used against Ulti. What can he do against Kaido , Lucci can't even come close to what he did, luffy was at yc1 level even without using acoc but even g4 luffy is not enough for Lucci and He needs to use Gear 5? Then Blackbeard can't be yonko level because he uses two devil fruits + haki against Law
Stupid though.
1n his base stats increase even more fighting kaido which means base luffy is resounding more powerful than his early wano counter part yet that luffy felt the need to use g5. The same way luffu felt the need to use g4 against ulti. Which directly means awakened lucci >g4 luffy. It's PLOT bro remember lol.
PLOT is also why blackbeard needed two fruits and haki to best law
Lucci does more than kidd since lucci has a way of internal destruction on kaido so.......
It's simple really if base luffy is all that took to defeat awakened lucci oda would have written it that way. He didn't. So there is 0 discussion or argument on this