This team is laid out to bluff the lead Gengar, but then actually lead off with either Vaporeon or Ferrothorn, depending on what lead the opponent seems to be using. The rest is explained below.
Gengar (M) @ Choice Scarf
Trait: Levitate
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)...