At first glance, it appears you intend to use Vibrava's Sand Pulse attack (of your active Flygon) via Celebi EX's Ability. You'll inflict damage onto the defending Poké, as well as spread damage onto your opponent's benched Poké. On top of all that, you'll also get the added damage counter drop via Flygon's Sand Slammer. Nice deck concept.
As one who has built and successfully played a Flygon deck, following are some suggestions:
-7 G energy,
+1 DC energy,
+4 F energy. You have no energy attachment acceleration abilities; so, your opponent, chances are, would not give you the opportunity to fully load a Flygon with energy. Secondly, Flygon's attack doesn't really compliment the deck's intended spread strategy (my assumption). Hence, I believe these G energy slots could serve you better in other areas.
-1 Dusknoir,
-1 Duskull. I've found a 2-1-2 Duknoir line to be quite sufficient. Plus, you really don't want to start with a Duskull - no surprise later. Since you need some more basic Poké, following are a few alternatives to consider:
- Ditto. This Poké can "mask" what you might play next. No energy re-mix required.
- Emolga. A 70 HP, free retreating basic Poké has a Call for Family attack (for just C energy cost). No energy re-mix required.
+1 Vibrava. I suggest you max these since this is your primary attacker.
-2 Max Potion. IMHO, Max Potions are ineffective in this deck. Expect your Poké to be 1HKOd because of other mainstream Poké being able to 1HKO them due to your Poké weakness.
-1 Pokémon Catcher. In this deck's case, you are not primarily gusting an opponent's benched Poké to the active spot to KO it. I believe one will tend to do this more as a defensive action to buy you time and/or forcing your opponent to have the Switch. Also, since you are spreading damage, dropping damage counters, and moving damage counters around, none of your opponent's Poké can avoid damage infliction. Lastly, with the popularity of Keldeo EX, its Ability will just transfer the defending Poké back to the bench. So, your need for Catchers is not as great.
-1 Switch. I believe 2 are sufficient.
+3 Crushing Hammer. These will help slow your opponent's energy build-up, especially if he/she does have any type of energy attachment acceleration.
-2 Skyla,
+1 Computer Search,
+3 Cheren. I believe you need more card drawing support.
Regarding game strategy: you will some tough match-ups with the tier 1 decks (e.g., Blastoise-Keldeo EX, Hydreigon-Darkrai EX, Eels-Raquaza / Mewtwo EX / Tornadus EX, etc.) since they have big HP basic that can take the damage. Unfortunately, you must expose your Celebi EX in order to really leverage your main attacker
and Sand Slammer together. On the other hand, if you can just attack with Vibrava and get away with it (lol), do so!
Your opponents will figure out the key to defeating this deck is KOing Dusknoir. So, spread early and often. You may even need to sacrifice a Flygon or two before you catch up in prizes. Hopefully, you can play Dusknoir as a "suprise" in order to KO a critical opponent Poké and/or multiple opponent's Poké.
Another key concern I have in playing this deck is being able to take enough prizes within the game time limit. So, you'll need to be mindful of the clock.
I hope these comments helped. Have fun!
Follow-on edits/comments:
11/21 - I forgot to mention another cool tactic: With Celebi EX in play, you can also use Trapinch's attack (of your active Flygon), Smithereen Smash, to possibly remove an energy from the defending Poké. One more "trick" in the bag (while you're perhaps waiting to get 3 energy onto your active Flygon to attack with Vibrava).