Skuntank (although quite a charismatic evil Poke)
Because they either a) look horrible, or b) are useless.
DPPt had the worst starters of all generations, even compared to Hoenn with Treeko and Mudkip. Between both generations, the bird starters - Piplup and Torchic - were the only aesthetically-pleasing ones. Hoenn only beats DPPt because of the whole Mudkip meme.