>>19181320The only thing that hurts muk is its level-up movepool.
It learns almost exclusively Special moves, and grimer is too slow to really be worth leveling up if you dont start close to its evolution; Because it was intended as a late-gamer, Grimer evolves at level 39, which is hell for anyone raising one in later games where you find them as early as level 8, especially due to the above point with the lack of a physical movepool outside of a few TMs... which it doesnt get much of.
Muk needs to get Earthquake. It gets Shadow Sneak instead. Priority is nice but a ghost move? No STAB on it, and the shittiest coverage option possible? defeats the whole purpose; You're better off racking up Poison or toxic damage than hoping to pick off weakened opponents with Shadow Sneak. It hurts psychics... a little, I guess. Still not enough attack to use it unless you;re fighting Kirlia or something