Rory-
Playing Shiftry DX alongside Shiftry ex is a mistake. DX needs to be active for its power to work, and you don't want them to have a stadium (Battle Frontier could be that stadium) on their side of the field, which is why you need to max Windstorm. If you're going to play any kind of backup Shiftry, play Shiftry LM - it compliments the Eeveelutions so much more nicely by letting you reuse their powers. Also, regardless of how many Eeveelutions you play, max DS Eevee for its Call for Family attack.