>>16484981>Something that can switch in, take the initial hit, take another hit after that, 1HKO, and live to tell the tale.252+ SpA Mega Gengar Shadow Ball vs. 4 HP / 252 SpD Assault Vest Spiritomb: 88-105 (36.3 - 43.3%) -- guaranteed 3HKO
252+ Atk Spiritomb Sucker Punch vs. 4 HP / 0 Def Mega Gengar: 272-324 (103.8 - 123.6%) -- guaranteed OHKO
>Also has access to Pursuit, which OHKOs on a switch>Also has Infiltrator as an ability, so it shits on Sub gengar>Also a Ghost Pokemon, so it can switch out of Shadow Tag if Gengar manages to Perish Song itHere's your hard counter.
Regardless, that's a stupid question. There are ALOT of pokemon in OU that can 2HKO most pokemon that switch into it, provided they predict accurately with their moves. And Gengar isnt too bulky.
The problem lies in Perish Song working in tandem with Shadow Tag. There are plenty that could revenge kill it, but the moment they come in, Gengar can perish song. That means it's very, very easy for your M-Gengar to guarentee kill at least 2 mons to your one, minimum. And most ghosts that get out of shadow tag gets fucked up pretty bad by shadowball.
Really, you take Perish Song away from M-Gengar, and he's not that scary. A regular Gengar would be more annoying overall without PS.