One piece is not a serious manga more goofy you are more powerful you are.
19 years and defeat a yonko with only one serious attack is enough for me to understand Luffy is just have is own league
None of this are valid arguments.
One Piece not being a serious manga doesn't mean MC is the top 1 all time.
Nowhere at One Piece says the more goofy you are the more powerful you are. No one is more goofy than Usopp, Luffy included.
Luffy didn't defeated Kaido with only one serious attack. Even if Kaido had take Senzu Bean or that Medicine Pill that Zoro took before Luffy ultimate wouldn't be considered only one serious attack.
How the hell you try to make an argument about being stronger by being goofier than you change to being strong by using a serious attack.
And all Luffy's attack with G5 were serious. And before you make the classic argument, no named attacks are not weaker than named attacks.