The following grind my gears to the max:
>GF comes up with a pokemon concept that, on its own, would be totally broken
>To counterbalance this, they nerf it somehow
>They always over-nerf it to the point where it's unusable
I'm talking about guys like Regigigas, Slaking, Shedinja, Sableye (pre-prankster), etc.
Also, in general, the fact that they don't try to balance pokemon whatsoever. I'm not expecting all pokemon to be perfectly balanced by any means, but I wish they'd at least TRY to make certain pokemon at least a little bit viable. But really, why spend the effort designing things like ANOTHER early-game normal/flying bird or another weak 2-stage rodent or the countless horrible bug pokemon? With just a couple stat/move tweaks, they could've at least been usable. But no, they had to make them completely worthless. WHY?
One last thing: each game has that one fisherman with 6 magikarps. Seriously GF, cut that out.