Got a better idea, cuze I had the same idea as you, but my decklist was this:
21
4 Mew Prime
2-2 Creselia/Darkrai LEGEND
2 Crobat Prime
4-3-4 Gengar
9 Phisic Energy
(SUPURTER/TRAINERS/STADIUM) Haven't think about that. S:
Its a great idea since their retreat cost is free (except...