Gengar's Creep Show attack knocks out Pokemon with three or more damage counters on it. With Roxie, Weezing, and Haunter, you can easily get more than three damage counters for easy knock outs. Better yet, Gastly sets up Gengars faster than ever because when it's knocked out, it puts two haunter on your bench. When it becomes your turn afterward, you can evolve the Haunters into Gengars on your second turn! Additionally, Gengar and Weezing can attack for only one psyhcic energy thanks to Dimension Valley. Have fun!