Darkrai Vstar, Galarian Moltres V

I love Darkrai, so you caught my attention with this deck. Your choice of Pokémon is solid enough (you might consider playing Weavile GX for its ability), but your list of trainers is suboptimal IMO.  Firstly, drawing through this deck looks like it would be a slow and arduous process on paper. The Crobats are great and Radiant Greninja helps a bit, but your only supporter for draw is Marnie. I can see playing one copy of Marnie for early game hand disruption, but, overall, N (and soon Iono) is arguably the stronger card for hand disruption. For draw, I would go 1 Marnie, 1 N, 2 Colress (PLS 118), and 1 or 2 Professor's Research, as well as a couple copies of VS Seeker. You might also consider playing Sky Field to expand your bench to make room for those Crobats. Lastly, Darkrai GX has a powerful GX move, but you'll rarely be able to take advantage of it in this deck as currently constructed. You have a couple Pokémon that can apply status conditions to the opponent's active with their attacks, but you can't count on those Pokémon sticking around with said condition until the following turn for Darkrai to take the KO. You need to be able to apply a status condition the same turn you attack with Darkrai GX. Their many Pokémon with abilities that apply status conditions that could do the job, but the simplest solution is to play a couple copies of Hypnotoxic Laser.

Thanks for the feedback! I will change the trainer cards according to your feedback. Which cards do you think I should cut off to make these trainer changes? Also, I was using Darkrai GX primarily for its ability rather than its GX move. Is not its ability good enough to include it on its own? If not, is cutting it off or adding some copies of "Hypnotoxic Laser" better?

Apologies that I'm just now seeing your response,wari !

Regarding Darkrai GX, I would suggest cutting it over adding cards to better utilize it. You have plenty of 2 prize bench-sitting liabilities in the deck as it, between Crobat V, Galarian Moltres V and Darkrai EX so GX would need to have a pretty amazing ability to justify inclusion in my deck. While Darkrai GXs ability does synergize with VSTAR, it's FAR from amazing. It's essentially a restrictive Dark Patch (since you don't have a choice where to put the energy) that comes at the cost of crowding the bench and giving up 2 prizes for 180 HP. Considering you play 4 Dark Patches (as you should) and can recover 2 more if you wanted with Darkrai VSTAR, allowing you to bench the Pokemon from your discard pile, so Darkrai GX is superfluous. 

On a similar note, I would replace Darkrai Prism Star with the Galarian Moltres from Evolving Skies. Moltres has the same ability, but a more useful attack.

With respect to cuttable cards, I think at least one energy recycler and two max elixers can go. You have many ways of moving energy from the discard pile to your board and part of the decks strategy is to get a fair bit of energy into the discard pile ASAP, so playing energy recycler really won't make sense except for certain late game situations. When playing max elixirs, 13 energy cards is really the minimum number you want to get good return. As your deck is constructed, it makes sense to play an elixir in the early game and perhaps you may want to play recycler and then an elixir late in the game. In the mid-game, you likely will have thinned out a good chunk of energy and get value on elixirs. So, it's really a situationally useful card, which makes it cuttable. If you swap in Galarian Moltres (a late game attacker) as I suggest, you'll want energy in hand for it, which further decreases the value of the elixirs.

Trainer's mail is a fine card, but is less valuable than the draw supporters, so would be worth cutting some or all if needed.

Lastly, I get why you put in Darkrai EX, but if you may find playing this deck that the bench space is more valuable than deck space. That is, it would be worth cutting EX for some combo of Hiding Darkness Energy and Float Stone. And my final suggestion is to include a card that allows you to recover Pokemon. There are probably better options that aren't coming to mind right now, but something like Ordinary Rod could work and would serve the dual purpose of getting back a couple energy cards, allowing you to more comfortably cut both energy recyclers.