I would have to say Plusle or Minin or Roselia. They are the most pointless characters, crap stats and are semi-clones of other pokemon *cough*Pikachu&Bellossom*cough*
Illumise and Volbeat.... what is with those things? They look like disney characters. There's probably others but that's the last time I can remember thinking 'I hate those things".
totodile etc were the best out of the starters for the neo series, i thought. Chikorita and Cyndaquil were pretty crappily designed, as was Blaziken. The originals were the best. (I liked Charizard, though not coz i thought it powerful.)