Buggy is literally a gag character, that's his existence, he might as well be Oda's self insert with the level of plot armor he has, him being a Yonko is no different from Nami hurting Luffy/Zoro, it happened because Oda wanted it to happen and thought it would be comical.
It's not an exception, Buggy being made a Yonko is clearly a gag, like, you have to be delusional or in denial to claim otherwise
- His crew is straight fodder and we know this because Hajrudin who was one shot by DR Luffy was one of his strongest members
- He has zero known territory
- He's far, far weaker than even Enies Lobby Luffy
There's not a single thing he has that could make him a Yonko except plot armor
To claim you don't need to be strong to be a Yonko is just plain retarded, when we're first introduced to them as a concept they're literally referred to as the strongest pirates in the world by Garp, pretending that you only need a bit of notoriety and a fodder crew to be one is joke worthy.
Also you're clearly misinterpreting what I'm saying, I never said being strong individually was all you need to be a Yonko, you obviously need a decent crew and other things as well.