I play this deck a lot on PTCGO and so far nothing from the new set makes this deck any better, but there might be something good. The deck already hits 190 using AT Golurk. (Who is actually your main attacker in some games). The Xerneas BREAK could be good but it needs 160 HP or a powerful ability so it's worth using over FFB and we might get a basic/stage 1 dual type that actually fits in the deck.
EX cards cause a prize race for your opponent. I do run 2 Shaymin-EX but I also run 7 types so I can fill my bench and still do full damage well forcing my opponent into taking 6 prizes. Filling the deck up with EX cards just gives your opponent a faster prize race. More so if you are running so many: odds are that they might have a type advantage on one of your EX cards and can easily OHKO with a Lysander.
There are also what I consider core poekmon to the deck and having any overlapping types with them makes that pokemon redundant. Fairy is the main one, as your main attacker you should always have one on the bench getting powered up or ready to go. AT Golurk is Psychic and Fighting and is my main attacker against things like Jolteon, Mewtwo, and Alakazam. I also run Octillery as a great bench warmer that helps me keep my hand up when I don't want to play Shaymin-EX.
That leaves me with 3 extra types. I use Druddigon, he hits 90 for a DCE and a FFB after I loose a pokemon and is a basic so I don't need to worry about evolving; Zoroark, as a solid back-up for just a DCE; and Shaymin-EX just so I can "set-up" and to give me a 7th type to OHKO M Ray. Currently the only other cards that really fit are Vespiqueen, as a late game sweeper or Greninja counter, (Gininja is actually a big problem for this deck) and Stardust Jirachi, just as a stall or disruption.
So far nothing from the new set adds anything to this deck. Volcanion-EX gives two free prizes to a bad match-up, shares a type with Octillery, and as an EX can loose you the prize race. M Gardevoir and Azumarill have all their types covered. M Steelix offers one new type but there is no reason to play it when you could just run a Promo Jirachi in it's place and do better. Shiftry offers two new types but being a stage 2 means that you'd have to devote too much to get it into play. We need a dual type stage 1 that could replace Zoroark (Or Vespiqueen in that slot) or a dual type basic; again, not being Fairy, Psychic, Fighting, or Water.