Agree with the 3 Gardevoir SW rather then 2 level X. Having the speed of your deck is important.
Given all the LV.X pokemon, it might be amusing to try removing three cards for one Premier Ball, one Palkia, and one Palkia LV.X. The LV.X gives you complete control over who's active, allowing Empoleon to snipe safely, or donk an irratating Gardevoir with your own Gardevoir + Lake Boundary.
Could be worth a shot, as it's not that much to fit in to give yourself an even stronger lock.