Wallbreaker/Stallbreaker
Pokémon that excel at punching holes through the opponent's team: especially opposing walls.
Wall
Pokémon that specialize in stalling and shutting down opposing offences. Most walls specialize in physical OR special defense.
Attacker/Offence
Pokémon that specialize in offence right off the bat, without setup needed. However, they are often frail and easy to pick off.
Sweeper
Pokémon that, with setup, are meant to beat entire teams, but often require support.
Pivot
Pokémon that specialize in entering and exiting battle while effecting your team or the opposing team.