Aerodactyl

At first glance, Aerodactyl seems like a rather nondescript Pokemon. Sure, it's fast and has access to Taunt and STAB Rock Slide, but it doesn't hit very hard at all, possesses a weak Flying-type STAB, and has weaknesses to a plethora of common types. However, Aerodactyl was given a subtle but huge improvement in its Dream World ability: Unnerve. Unnerve prevents the opponent's Pokemon from using any of their berries, which means there is no more Yache for Garchomp, Charti for Thundurus, Chople for Scrafty, Occa for Scizor, Shuca for Metagross, Coba for Amoonguss, or Sitrus or Lum for anything. This can be an incredibly potent way to assure KOs with Pokemon that can otherwise be stymied by common resistance berries. This simple change makes Aerodactyl a useful team player, and helps it in its own right against the common users of Charti and Coba Berries.