I'm not the kind of guy who actually DISLIKE pokemons. I think all of them are cool in some way. Hell, even Miltank. If it was on your team, you better believe you would love that pokemon.
Anywho, there is ONE pokemon that I find... disturbing.
That's right, Amoonguss. I mean what-da-f**k? An other mushroom? Did pokemon scientists forced a Shroomish to mate with an Electrode? Just looking at it repulses me! Not only that, but the NAME! Read it out loud! It sounds like "A Moon Guss"! What the f**k is a moon guss? Is it the result of the moon blowing the most idiotic pokemon ever? Arceus!
Anyway... WAIT, I'm not done yet!
If you look at the pokedex entry, it clearly says that "It lures prey close by dancing and waving its arm caps, which resemble Poké Balls, in a swaying motion". In other words, it seems that it thinks that he resembles to a pokeball so much, that he only needs to wiggle to catch some prey! What kind of stupidly dumb pokemon would fall for that?! Why the hell would a pokemon go to a pokeball anyway?! It's like frekin' prison!
(Wow... ok, kinda wrote what was in my mind there :/)