Revenge Killing is one tactic. That is when the opponents Pokemon are weak and you send a Choiced Pokemon to finish them off after your last one faints.
Salamence (M) @ Choice Scarf
EVs: 4 HP / 252 Atk / 252 Spd
Adamant Nature (+Atk, -SAtk) or Jolly Nature (+Spd, -SAtk)
- Aerial Ace
- Rock Slide/ Brick Break
Choice Scarf makes him fast enough to outspeed most Pokemon. With Moxie, he gets an Atk boost for every knockout, make him go from Revenge Killer to Sweeper.