Azumarill @ Assault Vest
Ability: Huge Power
EVs: 240 HP / 252 Atk / 16 SpD
Adamant Nature
- Aqua Jet
- Play Rough
- Knock Off
- Waterfall
Appreciating the support offered from Heal Pulsr, Azu would make an excellent partner while carrying an Assault Vest. Being as it lacks recovery, it can abuse this to stay alive as it tanks hits. But this does not ensure that you beat Gengar and other Poisons such as Mega Venusaur, so I'd suggest you use more type variety to cover said types.
Togekiss @ Leftovers
Ability: Serene Grace
EVs: 248 HP / 8 SpA / 252 SpD
Calm Nature
- Roost
- Air Slash
- Thunder Wave
- Heal Bell
Togekiss helps beat the likes of MVenusaur and Amoonguss, while crippling other Mons with its TWave support. But again, this often loses to Gengar so it won't do much but just Paralyze it.
Klefki @ Sitrus Berry
Ability: Prankster
EVs: 252 HP / 164 Def / 94 SpD
Calm Nature
- Safeguard
- Swagger
- Foul Play
- Protect
The evil set is here. Abusing SwagPlay, this can be used to beat the likes of Gengar by wittling it down with the ParaFusion strategy. Being banned from regular play by Smogon, this specific strategy is beyond evil and says something if it got banned. Foul Play makes fainting the opposing Pokemon easier when abused witg Swagger, formally known as SwagPlay.