Toxic Gas (Poké-Body)
As long as Muk ex is your Active Pokémon, ignore all Poké-Powers and Poké-Bodies other than Toxic Gas.
Poison Breath
Cost: Grass (10)
The Defending Pokémon is now Poisoned.
Slimy Water
Cost: Grass, Grass, Colorless (40+)
Does 40 damage plus 10 more damage for each Colorless Energy in the Defending Pokémon's Retreat Cost (after applying effects to the Retreat Cost).