Here's my take on the list, trying to take into account thoughts and changes from previous posts, as well as implementing some ideas of my own.
Pokemon - 15
4 Xerneas
2-2 Joltik/Galvantula
2-2 Pawniard/Bisharp
1 Volcanion EX
1 Shaymin EX
1 Mew
First, I maxed out the Xerneas because it's our preferred starter. I also added a second copy of Bisharp because only playing one copy is risky business and the prize card gods WILL punish us for it.
I think it's necessary to add a second copy of Shaymin as well, but Javi put the kibosh on using more than one, so I left it out. Since we're not playing Sky Field, I removed the safeguard Carbink and one Mew, because all they do is muddy up our available bench spaces with single-types instead of the preferred dual-types. One Mew is still absolutely necessary though, in my opinion, as it can easily OHKO M Mewtwo before they can get Garbodor rolling.
Possible additions:
1-2 copies of Xerneas BREAK for the HP buff and an instant transition into a non-basic attacker, though I think we have plenty of coverage between Galvantula, Bisharp, and Pokemon Ranger to ward off potential Jolteon locks. Also, the BREAKs would negate our Fighting Fury Belts, so if we do play the BREAK variant, swap FFB for EXP. Share.
Supporters - 10
3 Professor Sycamore
3 N
2 Lysandre
1 Pokemon Ranger
1 Ninja Boy
This is the skeleton list I've been using for almost every new format deck I've built so far, and it's been working out quite nicely. If there's space, playing full four counts of Sycamore and/or N would be ideal, but I never seem to be wanting for draw supporters when playing a six card split between them (3-3 here and for other evolution-based decks, 4-2 for more aggro decks). The only other addition was Ninja Boy, because he's the bees knees.
Possible additions:
1 Hex Maniac to slow down both Greninja BREAK and Yanmega BREAK, the biggest threats to this deck in my opinion, as they can deal damage cheaply and keep up in the prize trade.
1 Giovanni's Scheme to help hit the right numbers against Megas, especially if we get hit with a Parallel City.
Items/Tools/Stadiums - 23
4 Vs Seeker
4 Ultra Ball
4 Max Elixir* (See below...)
3 Trainer's Mail
2 Level Ball
1 Super Rod
2 Fighting Fury Belt
2 Fairy Garden
1 Parallel City
I maxed out VS Seeker because they're just too good, even without the Battle Compressor synergy. I dropped a copy Super Rod, but I could definitely see playing another. I only play one in my Garchomp deck, which has a lot more moving parts, and I very rarely feel the lack unless I have to discard it away early. I prefer Fairy Garden as the primary stadium because of the flexibility it provides. In a Sky Field Variant, with Zoroark instead of Bisharp, then maybe I'd consider Float Stone, but cards like Manaphy EX and Darkrai EX have proven the power of universal free retreat and it's just too good to pass up if we're playing with Fairy Energy. One tech Parallel City is just too useful in too many situations to leave out, even if it results in limiting our own bench space, as we can still hit HUGE numbers if we build up our board right (1 Volcanion EX, 1 Bisharp, 1 Galvantula = 190 [60+60+60+10] even without a FFB). (See Max Elixir discussion below...)
Possible additions:
2 EXP. Share to keep energies on the board.
1 Enhanced Hammer to frustrate anyone playing DCEs and DDEs.
Energies - 12
4 DCE
8 Fairy Energy
I have 12 energies because I like the feel of a deck with 12 energies, that is all. I believe we could probably go as low as 5 basic energies and be fine, but we WILL have games where we can't find the necessary energy to attack turn 2 and that's never good. IF we are going to play Max Elixir in this deck, then I really think we must play AT LEAST 10 basic energies. I've tested the crap out of Max Elixir-based decks ever since the card was released, so even though I'm no math whiz, I know this from experience: anything less than 10 basic energies and we'll be LUCKY to hit our Elixirs 50% of the time, and it's most likely 25%. I'd love to see the actual math on this, especially if it proves me wrong, but I'm almost certain I'm right. That said, there's a counter argument to make: even if we only hit one Max Elixir the entire game - which, if we play 8 basics, we probably only WOULD hit only one every game - then that may be plenty of acceleration to get this deck rolling, which is enough to warrant a full four count. That's the only thing I have yet to test with this deck, so any other info/input would be great.
Total Cards: 60, unless we decide to roll without Max Elixir, then I'd add a fourth Trainer's Mail, notch the basic energy count down a tad and have 3-5 more cards to play with.