So, hear me out of this. Theorymon away!
Gengar @ Gengarite
Levitate -> Shadow Tag
Timid Nature
252 Speed, 252 HP, 4 Defense (modify HP for 4 subs, whatever that adds up to)
Protect
Substitute
Perish Song
Taunt
lolwut, no attacks? Well, why not? Gengar takes a crap on any attackers slower than it without any attacks anyways, so Shadow Ball is only really for last ditch damage. Why not stop defensive 'mons from setting up? Pokemon like Hippowdon, Smeargle, Ferrothorn, etc. are never going to beat Gengar, so their last moments will be spent trying to set up hazards, or possibly Whirlwind or Roar Gengar out as it tries to sub, freeing themselves from Shadow Tag in time to escape unharmed. Gengar can stop them by using Taunt on a predicted status move (and when you try to trap Skarmory, its pretty obvious when that's going to happen), then set up Perish Song and stall them out quite easily.
This makes Gengar an awesome anti-lead and trapper, in the sense that it can shut down attempts to start something early on in a match with little opposition, provided you play it right and your opponent doesn't expect Taunt. The only things that can beat it are faster Taunt (because it is Taunt bait like this) and faster attackers that can stop it from being able to sub (+75%).