Note that this is for FOURTH GENERATION OU!
Gengar @ Life Orb
EVs: 40 Atk / 224 SAtk / 244 Spd
Hasty Nature (+Spd, -Def)
- Shadow Ball
- Hidden Power [Fire]
- Focus Blast
One of the few sets that hasn't let me down since returning to Gen 4. I love Life Orb Gengar. My personal opinion is that the Sub/3 attacks set is a total waste because Gengar really needs that extra kick from Life Orb. Okay, you're safe from Scizor and ScarfTar (usually), but you aren't actually going to deal much damage, so what's the point? It's useless against stall and can't actually score crucial KOs against many Pokemon you see on offense teams. (As for SubSplit, I hate relying on Focus Blast in any capacity and find it to be underwhelming, though I think it's still a good set when used well.)
Enter Life Orb Gengar. One of the awesome things about all of the Substitute sets Gengar runs is that no one expects Explosion, and the Attack EVs ensure a OHKO on max/max Bold Blissey. You may want to scout for Protect but otherwise Blissey will stay in to get shelled. Explosion is also very useful for taking out Suicune, a Pokemon that sometimes comes in that screams "my opponent doesn't have a Gengar counter lol" even though it may not KO entirely. Hugely useful.
Scizor and Tyranitar are indeed annoying. I find Scizor pretty easy to predict--I often nab them on the switch with HP Fire. Tyranitar usually plays it safe or lures a Shadow Ball and is then guaranteed a free kill. As such, I have used this with Pokemon that can set up on Pursuit so Gengar's death isn't totally in vain.
Anyway, for all two of you who play DPP OU, Gengar is awesome. Its Speed is so handy and its typing/Levitate give it a ton of defensive utility despite its frailty, and I find him to be my favorite member of my offensive cores