I've been posting a lot of replies to Darkrai/Hydreigon decks recently!
I'll give you a few of my opinions about your deck list! I have been testing Darkrai/Hydreigon for the last three weeks or so and have really enjoyed it thus far.
Ultra Ball and Level Ball provide a great Pokemon search engine for this deck. Heavy Ball is not necessary because you have Ultra Ball (of which three is a great amount) which can search out Hydreigon from your deck. Ultra Ball combined with your other draw cards will allow you to play Hydreigon consistently. Having only one of a Trainer card in the BLW-On format will end up hurting the consistency of your deck, especially with the loss of Junk Arm. It will be very hard to draw that one card when you need it the most. You already have enough search power to consistently draw Hydreigon so I would drop your Heavy Ball and add a Level Ball. Level Ball allows you to pull Deino, Zweilous, Sableye and Sigilyph. Having two will boost the consistency of you drawing it when you need it.
-1 Heavy Ball
+1 Level Ball
I noticed that you have two Eviolite and one Rescue Scarf in your list. May I ask why? I'm assuming you want the Rescue Scarf for Hydreigon? Like I mentioned above, having only one of a specific Trainer card will make it very hard to draw when needed. Rescue Scarf might be a bit easier to play considering you can drop it on a Deino as soon as you draw into it, however I don't think it is necessary to the strategy of the deck. It's more of a card that would be great in certain situations but won't be used as much as some other cards that could be put in its place. I recommend dropping the Rescue Scarf and adding another Random Receiver. Increasing your count of Random Receiver to two will increase its consistency. It is a card that I use a lot. It's great when you have no Supporter cards in your hand and it's also beneficial when you have a Supporter in hand that you would rather not play. In that situation Random Receiver gives you a chance at drawing and playing a different Supporter. it can also be retrieved via Sableye's Junk Hunt.
-1 Rescue Scarf
+1 Random Receiver
I tested the deck for about a week using two DRX Hydreigon and one NVI Hydreigon and unfortunately never played the NVI Hydreigon the way I intended. It ended up hurting my chances of getting the DRX Hydreigon in play and took up a space both in the deck and on the bench. I ended up switching to three DRX Hydreigon and zero NVI Hydreigon. Do you find that you're able to play the NVI Hydreigon effectively? If so, I would love it if you would share your experiences with it!
-1 NVI Hydreigon
+1 DRX Hydreigon
In terms of your questions:
1) I haven't used Virizion myself, however I have tested with ShayminEX and ultimately dropped it. I found myself discarding it almost every game. It is terrible starting with a lone ShayminEX and when the end of the game came around I was never able to play it to my advantage, mostly because DarkraiEX was sufficient enough to win the game. Even if you could use ShayminEX to snatch a victory from the jaws of defeat, your Hydreigon will most likely have been Knocked Out and it will be tough to set up ShayminEX with the required energy.
2) I haven't used MewtwoEX but I feel that Sigilyph is the better play. Both Pokemon can be set up with Dark Trance, however Sigilyph can be used to stall against your opponent's EX Pokemon and only gives up one prize.
3) I prefer Bianca over Cheren. I find myself laying down a lot of cards from my hand, Ultra Ball and Professor Juniper. Usually at the very least Bianca will net me three cards and it has been well known to net me four to six cards! Obviously drawing six cards with Bianca is a fairly rare occurrence but I'm almost always able to draw three. Bianca can also really help you recover from a late game N.
4) I believe I answered that somewhere above
.
I hope this information helps out and isn't "TL;DR"
. My suggestions are just that, play what works best for you!
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