Vullaby can take advantage of this core and even set up in the end.
Vullaby @ Eviolite
Ability: Overcoat
Level: 5
EVs: 236 SpA / 236 SpD / 36 Spe
Modest Nature
- Dark Pulse
- Roost
- Taunt
- Nasty Plot
Basically, it Taunts Koffing so it can't Pain Split (at some point), and Roosts off any...