not really, it also gets Nasty Plot and Calm Mind, something Gengar doesn't, but this is doubles, so yea.......
Other than that, Gengar has
1- Stronger Shadow Ball
2- Faster(can speed tie w/ Latios)
3- Focus Blast(better than HP Fighting)
4- Thunderbolt/Sludge Bomb, two cool moves to use
Well, I guess Power Gem is nice to screw w/ Volcarona, but yea, Gengar is better in almost every situation