Gengar - Double Dark

I have one at level-20 that I haven't powered-up. I think the issue is that Dark Pulse is such an ineffective move that one of Gengar's other charge moves would work about as well type neutral as Dark Pulse would with the advantage.

gengar has stab ghost type moveset that has similar coverage ad better dps (dark pulse and shadow ball have the same attack speed, but dark pulse has a bp of 80 while shadow ball has a bp of100) plus shadow ball benefits from stab, while dark pulse doesn't, and they are both se against ghost and psychic only, the only scenario where dark pulse outperforms other gengar charged moves, is against girafarig and girafarig only, because against normal types like blissey, you'll better use sludge bomb or focus blast