Sometimes I led with Salamence, and it turned out to be good for softening up things like physical attackers so Blissey could come and Toxic it. Particularly useful for scouting Draco Meteors too (Usually if it says "White Herb restored its status", It'd usually have Draco Meteor if it could learn it, like Garchomp, thus a switch to Blissey to absorb a predicted Meteor and Softboiled off the damage) I played around a little bit and saw Counter Sash Gengar worked better as a lead though, so Mence would usually sit back for cleanup duty, came out mostly if something Double Teamed. Usually I'd use a shuffle strategy where if I saw that something knew Earthquake/Cross Chop/Shadow Ball/Return I'd switch between Blissey/Gengar and Blissey/Mence to deplete PP and in the Blissey/Mence case, lower attack drastically (Did it to Slaking once, I think I ended up Dragon Dancing and sweeping that trainer).
Hippowdon usually gave me some problems with Sandstream nullifying Focus Sash, but I usually Countered or Toxiced it to death with Bliss. Rest Bronzong made me resort to stalling it out until it died to either struggle or Seismic Toss.
IVs and EVs are as follows
Gengar - Modest
IVs (8/29/30/31/26/28 Not the best Gengar, but I'm planning on rebreeding one that's Timid/Modest/Hasty with my quint flawless Misdreavus as soon as I'm done breeding Duskulls)
EVs 6 Hp/252Sp Atk/252 Speed
IVs 28-29/x/31/x/31/x Got tired of breeding and decided to keep this
EVs 252 HP/252Def /6 Sp.Def
IVs 29/31/31/19/31/31 (Close to perfect, what more could you want?)
EVs 6HP/252 Atk/252 Speed
I think I lost because something either used a OHKO move or criticaled on Blissey, and after Sala killed it, left me with Salamence vs. Tentacruel (Same base speed). AI won the coin toss, and as expected, Ice Beamed. Maybe I'll put a Yache Berry next time and see how that works.