I'm not sure if you don't want to make this a dark box but I have a few possibly pointers.
Draw support; I think that you could run a few more draw supporters. I personally would suggest running 1 N supporter. I would cut either 1 Parallel City, or possibly 1 Darkrai GEN Promo.
Darkrai GEN Promo ; I like the idea of Sleep stalling and getting KO's this way, but like
@WhiteWolfos, I think that having the Goodnight Babies Hypno (BKT) is a better choice for sleep. If you run Darkrai Promo to fuel Darkrai EX's second attack, its kind of unnecessary and inconsistent. If anything, you should run a few Baby Yveltal (Yveltal XY/GEN) to fuel a Dark Pulse for Darkrai EX to hit that extra damage. Damage wise, 80 damage and a double flip Sleep Condition is rather nice, but it's a bit slow and inconsistent. I personally think that the Sleep aspect in this deck is a bit inconsistent as it can be removed simply from being switched out and other aspects e.g. Pokémon Centre Lady. Special conditions aren't too much of a thing in Standard Format because of things like Memories of Dawn Mew, Zoroark, Talonflame and so on. Float stone and other trainers to switch (like Switch itself) eliminate sleep as well.
Personally, I would cut all 3 of the Darkrai GEN Promos for either of the Yveltals (both Fright Night & Oblivion Wing) and/or consistency cards E.g. +1 Trainers' Mail
Supporter Line; Like I said earlier, I would add more draw support, E.g. +1 N Supporter. I think it would be necessary to add one Pokemon Ranger to get out of Jolteon EX and Regice locks and other situations. I like the rest of the supporter line so I'm gonna leave it there.
A very solid list else wise to me, but remember, this is just my opinion.
Take it with a grain of salt, Rayquazatopaz34