Here's a list that I have been using that is very similar:
Pokemon:
3 Yveltal EX
1 Darkrai EX
2 Mewtwo EX
2 Yveltal XY
1 Charizard EX (CB)
2-2 Garbodor
Trainers/Supporters/Stadiums:
4 N
4 Juniper
2 Colress
2 Lysandre
2 Bicycle
4 Ultra Ball
3 Float Stone
3 Muscle Band
4 Hypnotoxic Laser
2 Virbank City Gym
1 Dowsing Machine - ACE-SPEC
3 Switch
1 Professor's Letter
Energy:
So basically, I tried to accomplish the same things, but make it less clunky and more consistent.
1 Darkrai instead of 2 because Darkrai is really only there for his ability. You don't ever want multiple of him filling up your bench space, because he just doesn't do enough damage for the amount of resources you have to pump into him. Yveltal EX and Mewtwo EX are simply better attackers and you want to be seeing them more often.
Keldeo EX is a good card, but not as much if you are running Garbodor and only 2 Float Stone. The free retreat from Darkrai and a good amount of Switches and potentially Energy Switch should fill his role better for this deck.
1 Charizard EX (CB): This card is just something I am going to test out for the Virizion/Genesect matchup. 3 colorless energy for 120 damage before Muscle Band and Laser can really help swing things our way. In other matchups, just use him as Ultra Ball fodder unless you're unfortunate enough to start off with him, but at least it's better than starting with Jirachi or Trubbish.
2 Colress and 2 Lysandre: With Donphan decks running rampant (not for long) 1 Lysandre just isn't enough. 2 was standard pre-Furious Fists, and after Donphan became popular, people ran 3 or 4 just to deal with that deck. I play 1 more Colress simply for more draw supporter consistency. If you feel safe with 9 draw supporters, that is perfectly fine by me. After thinking about playing against Seismitoad EX, I just now decided to take out the 2 Bicycle and replace them with 2 more Colress instead. I will see how that goes as I have read good things about that supporter set up in other places.
3 Float Stone instead of 2 because having your Garbodor shut off by Megaphone really sucks. If you are running Keldeo and no Dowsing Machine, I can't really see how 2 could be enough.
Switch vs Escape Rope: I just don't see the point of running a combination of Switch and Escape Rope because you just lose consistency in your strategy.
0 Startling Megaphone: I just don't feel like I have the space for it in my list, but I also don't think it would be my first pick to fill the last slot if I had room anyways. Personally, I would want to have more Lysandre, Colress, or add in Energy Switch if I have the space for multiple. Unless there is a specific matchup where this card is absolutely necessary, I just don't see how it is vital to the strategy. It's just a good card that messes up your opponent. I think Lysandre can mess up your opponent much more though. I can see the appeal of this card if you are running Keldeo and don't want opposing Garbodor to shut off his ability, but I don't like Keldeo in this deck in the first place.
0 Energy Switch: If I had the space, I would definitely run 3 of these. Maybe if I took out 1 Charizard, 1 Mewtwo, and 1 Ultra Ball, I would have the room. Great card for this deck.
Dowsing Machine vs Computer Search: Computer Search = early game consistency; Dowsing Machine = late game re usability. I don't think that Yveltal/Garbodor is fast enough to really be able to take advantage of Computer Search and that Dowsing Machine really fits the decks play style much better. Definitely personal preference though.
Most of this is just knit-picky small things. Overall, your deck is very good and you likely have lots of success with it. Lots of these small refinements really come down to personal preference and what you think is best against the current meta.
