Muk from Secret Wondera

[SabakuNoGaara]

ok so Muk's pokebody reads

Poke-Body Toxic Sludge: At the end of each player's turn, each of your opponent's Active Pokemon that has any Grass Energy attached to it is now Poisoned. If that Pokemon is already Poisoned, Toxic Sludge Poke-Body does nothing to that Pokemon.

so my question is if the defending pokemon has a rainbow energy attached (ex. Double Rainbow Energy, Holon's Castform) does Muk's Pokebody poison them? yes or no?

and if no, why not? DRE provides every type of energy and the BODY does not state BASIC energy just grass energy

 

[PokePop]

Yes. As long as it's providing Grass Energy (which it does unless something has shut it off).
So, if a Crystal Beach were in play, a DRE wouldn't. But otherwise, Muk will see it as Grass.