Always wondered why no one used Gengar in ubers...
Gengar @ Choice Scarf
EVs: 4HP / 252 SpA / 252 Spe
I've used this set for quite some time and it always catches people off guard. The main niche of this set is that it will always screw normal Arceus and any other rapid spinner. Trick will handicap both of them and Perish Song will phaze the former, especially after it has gotten a few boost with swords dance. Another good point about this set is its ability to shut down Blissey Chansey, +1 Dragon Dance Rayquaza and most CM Mewtwo. Another niche it has over most Scarf users is that base 110 speed and 3 immunities.