Roxie: For probably being one of the most badass-looking gym leaders and giving Ash such a hell of a time in the anime, she gets destroyed by L11 Magnemite and becomes its stepping stone to BW2 destruction. yeah >.>
Ghetsis: Hardest trainer in BW? Probably. BW2? Complete disappointment. Most especially his Hydreigon, who went from all-special to all-physical. um what.
also he suicided by his life orb, neat
Zinzolin: who's this crazy fucker stalking me with three fighting-weak pokemon with shit defense