➟ every story
I don't downright hate any pokémon, but the worst pokémon of all regions that comes to mind are Weedle, Zubat and Tentacool, yeah. Because of their tendencies to kill nuzlocke runs poison or confuse my pokémon. That's gamewise, though. I don't really dislike their designs or concepts otherwise, Tentacool I find especially cool, hehe.
Apart from Garbodor, I might say the Klink family or whatever they are really called. They are just... I just can't really enjoy a pokémon that looks that much like a machine and that little as something that is actually alive.
Mothim and Wormadam also come close, I never really understood why anyone would like to train that pokémon. So boring, mostly :p