>>14621465It doesn't have to be. Heliolisk has great Sp. Def, and all Gengar has to counter it is Focus Miss (and if you're running a Sand Veil Helio, then you can forget about that).
All Heliolisk has to do is endure an attack, and then it can use Electrify on Mega Gengar.
Then, Focus Miss does a measly 30%-35% damage (less if you've got Light Screen support or Helio manages to get in a Charge or two), while Shadow Ball only does 20%-22% damage.
All Heliolisk has to do is fire off a Thunderbolt, which does 56%-66% damage, meaning it's a guaranteed 2-hit KO.
Mud Slap and Bulldoze both do pretty piddly damage to M. Gengar, so they're not worth considering, and we have no idea about Egg Moves yet, so this is all pretty preliminary, but the outlook doesn't look good.