As for Gravity (on Triples only), I find Sashed Starmie to be very valuable. In the case that it isn't hit with attacks that KO it on turn one, it can actually do something back to the opponenet that is worth mentioning (STAB Hydro Pump, Blizzard, Thunder), and it is the fastest Gravity user aside from the Pranksters. But really, in either Doubles, or Triples, what is Sableye going to reliably do after setting up that Gravity?
And WTF? (sorry) NEVER.,.......EEEEEEEEEEEEEEEEeeeeeeeeeeeeeeeeeeevvvvvvvvvvvvvveeeeeeeeeeeeeeeeeeerrrrrrrrrrr use a Gengar on a Gravity team. One of Gengar's valuable selling points is it's Ground type immunity. Why would you even consider taking that away from a Poke that is a 110 base speed, and hits as hard as it does as it will run the risk of taking a super effective hit?
No, just...................... *face palm*..........................No.... Please, if you care about your ranking, never do that again.
In Triples, aside from non-STAB Dark Pulse, Gengar doesn't even have any other moves to hit non-adjacent Pokes. If you want
to use Gengar in Triples (although I wouldn't use it in either Doubles, or Triples), don't use it on a Gravity team.
I could see it's viable merits on other teams, however, on a Gravity team....Again, please........NO!!!!.... NO!!!!.... NO!!!!