Well, thats something hard, because i tend to pick only my favorite pokes, and the power and base stats are directly proportional to the coolness to me, so...
Eh, the worst pokemon ive ever used was Sunflora in HG/SS, only usable moves are grass-types, which are all piss weak until i got TM for giga drain n KANTO,, or energy ball and earth power since i was tired and took on the Battle Frontier for 4 hours straight, holy **** i spent my entire journey through Johto using bullet seed and return. But even then, it was less of a horrible poke in Kanto, where i could actually touch steel types and have a non-10 BP move to use.
and oh crap
a week
we're a week away
I cannot hold the tension