I did try out something like that. I once built a Mega Gardevoir deck with Latios EX thrown in for it to hold Double Dragon Energy. And Giratina is a good option for disruption, but you can one shot Mega Pokémon so it is not that big of a threat I believe. I also went and tried a Double Mega deck with Mega Gardevoir and the Dragon Mega Rayquaza. That last Dragon sure made the deck very scary to face but I had some trouble getting the right Energy, Spirit Link and Mega Evolution Pokémon at the right time sometimes. It was essentially playing two completely different things in the same deck, and ended up not going too well because of the clunk factor and that I was not running Shaymin EX (would I even have had room for them). I do appreciate the extra damage given by the fact that Double Dragon Energy gives off two Fairy Energy for Brilliant Arrow's damage, but the fact is that unlike how it is with Darkrai EX and Xerneas BREAK, there is no need to have nine or ten Energy on the board to one hit Knock Out basically any Pokémon. Only seven or eight are typically needed, or only five or six against non EX decks. Thus, Double Dragon Energy, although interesting to see in this deck, is far from necessary in it. This is proven by that the deck runs very well off 9 to 11 Energy cards that are all basic Energy. I also appreciate the feeling of being immune to Special Energy disruption very much. This makes decks like Raticate and Giratina have to do some more work to take me down.
As for Hoopa EX, I did test two copies of it that were thrown in at the place of some other cards. It did not take long to realize that it was excessive and unnecessary given the huge amount of Basic Pokémon I run and the draw power I normally have. It is true that it helps to thin out my deck to get better odds to hit a Max Elixir but on the other hand, none of my basic Pokémon are hard to reach for, not finding two Gardevoir EX on turn one really is not that bad and the space on my Bench is precious, also it is not before turn two that Despair Ray can be used.
Speaking of which, I plan to include a second copy of the Despair Ray Mega Gardevoir EX. The reason is that my deck needs to get going and dish out early damage, and there is that desire to clear my bench that only it can fulfill. It naturally seems like a good idea to include two Despair Ray Mega Gardevoir EX to get it out more consistently and even use two in a row if needed, and allow non EX matchups to become better for me.
