My vote is for Rayquaza ex. sure it's an ex worth two prizes but it has no weakness, it's great if you are behind. with lake boundary it can ohko empoleon and it already has an established tradition with GG. it's either that or Dusknoir & warp point, even more of a staple with GG decks. i know Empoleon players are all geeked up about the kind of damage it can do but unless you've got glaceon lvl x or a pokemon holding a cessation crystal reserved on your bench i don't see how Dusknoir is not going to be a total nightmare. Of course eeveelutions will run jolteon while both garchomp and porygon-z just need the right kinds of energy.