Don't capitalize every word of a sentence, bro. It's weird-looking.

Shadow Ball is better on Gengar than Shadow Punch. Gengar is another Pokemon whose Special Attack is higher than its Attack. It also covers the same types (Psychic and Ghost) that Dark Pulse does.

One move that could be devastating on Gengar is Explosion, oddly enough. If you're really desperate for a powerful attack and can't find a fourth one that you like, toss that on. It's not very versatile, but it makes for a good last-ditch effort if Gengar is being pummeled by a Mean Looker or something.