Keep in mind that Metal Links Bronzong is an XY Black Star Promo as well, so depending on where they choose to cut promos it may survive rotation.
As for decks to remain strong or kick in, I definitely think M Ray just keeps all the pieces to remain consistent and go crazy. The only major loss is Battle Compressor into Mega Turbo.
Similarly, Rainbow Force Xerneas has a good chance to go off. Between Ninja Boy, Hoopa, and dual types the deck could go far.
This concept benefits Xerneas as well, but the Water Box engine core could be pretty big in the future. Max Elixir + Energy Switch is a really strong engine and I think it benefits a ton of decks. Each type can benefit in some way. I think a strong contender if Greninja stays strong and Zygarde comes in is Trevenany EX. Along with Sceptile EX energy efficient Grass attackers just steam roll through with weakness.
I think Garbodor is going to be crazy strong without reliable tool removal. I feel like more self sufficient Pokemon with strong attacks and or health pools. As such Darkrai Garb will stay relevant. Solid efficiency, sturdy attackers, has access to high numbers.
Lack of turn one item lock, aside from Vileplume whose consistency would die down a lot, means stage two decks might actually be able to use Rare Candy again. If Garbodor doesn't run the whole meta a number of strong Stage 2 Pokemon might see play. I think Florges BREAKThrough has some pretty legit potential. Same with Magnezone BREAKThrough.
I believe that since the promo bronzong is a phantom forces stamped promo, it could go out along w/ its non-promo phantom forces print, meaning steel decks cannot accelerate easy... And with the upcoming addition of a new part-fire-type(Volcarona) that evolves from a pure-grass-type that can abuse AOR's Forest of Giant Plants to get to Volcarona(Larvesta) from Steam Siege, the upcoming new kids on block, especially Xerneas BREAK and the aforementioned Volcarona, can be aided by Garbotoxin and Bunnelby PRC, a T1 Wally and tool to lock Vileplume before it has a chance to show up in play, as well as Geomancy to get energy on to give Volcarona on the Xerneas BREAK user's second turn, so that, assuming DCE is attached on T1, it will be ready to use its Power Hurricane(attack) to KO Waters, Grasses AND Metals. After that, assuming Vileplume is KO'd, zero to one manual fairy energy attachments, depending on whether or not the DCE is discarded, can get it out of Active via Fairy Garden(replacing Forest of Giant Plants in process), and two further fairy energy attachments to Xerneas BREAK for powerful Life Streams could prove to be a formidable combo deck post-rotation with no worries about existing cards going away from Standard.
^ Here are four reasons that explain the above:
1. You can search for fairy energies in a similar manner to Delphox BREAK, but unlike the break, at the expense of your turn, and...
2. It could replace Darkrai-EX in a way, as Dark energy needed is not a way to make a deck as flawless as possible, as it pays to have the utility in terms of energy in deck when it comes to energy-influenced damage in today's metagame, meaning including DDE will likely not cut it: What if your dragons are in the discard? Prized? In that event, in today's meta, due to the damage output being severely crippled by the loss of Dragons to the prize/discard pile, and with it, the only way to get DDE attached to help Darkrai-ex shoot for the big numbers greater than 180(meaning that unless Darkrai-EX has a Fighting Fury Belt attached, assuming 8 Dark Energies, the standard for Darkrai-EX/Giratina-EX/Garb, the max output is not enough to KO Zygarde-EX, while Belt or no belt, Basic EXes that have a fighting fury belt attached cannot be 1HKO'd by the max output before Darkrai-EX is likely KO'd by the belt-wielder), you could be forced to scoop and hope for a better starting hand in game 2 if you do not have other options to put your double energy special on.
3. If you want an energy-dependent damage attacker, best to go with any pokemon that uses one energy type for 1-2 attack cost, can accelerate to attach to pokemon that either require that type and/or doesn't require a specific energy type to do peak damage, and doesn't need to go w/ a type-limited special energy card to do added damage. Besides, after this rotation, unless CP4 makes it stateside, Darkrai-ex will lose Shadow Circle, its sole Fighter counter, making Xerneas BREAK an improvement over a pokemon that does the same but risks getting hit by a weakness from a type that is OU as of now: Fighting-type. Especially those called Carbink BREAK, Garchomp BKP, Zygarde FCO, etc.
4. Also, in a way that changes the current meta, which has, before Steam Siege, colorless-peak-damage attackers that have hitches that limit their usefulness in 60-card decks due to long setup time and/or vulnerability to Hex(Golurk AOR), consistency issues(Delphox and/or Delphox BREAK), or even exposing the entire deck to getting hit by counters that push such attackers to discard in a way that cripples the deck should they be included in the deck hit by such counters(M Rayquaza-EX as well as M Mewtwo-EX (Y)) should they be included, has more choices regarding pokemon that can attack regardless of energy type in-set in a manner that puts existing pokemon to shame, as very few of them require no specific type of Energy for added power. Currently, M Mewtwo-EX(Y), Yanmega PHF, Golurk AOR, and Delphox FCO, among a select few others, are in a very rare kind of club: the All-Colorless Peak Power Attack Cost club!
^ Does the aforementioned Xerneas BREAK sound like a good idea for a new metagame deck?
^ Oh, and in case you have to throw away items or Specials before any Plume KO, Bunnelby could put the discards back in deck, including any Specials that have to be discarded by KOs from opposing Volcarona...
