Xerneas EX was one of the XY Black Star Promo cards, making it highly sought out and earning it a commemorative reprint in Celebrations
If youre one prize card away, it is a surefire way to end the game quickly with a clean knockout
The remainder of the deck is filled with standard Trainers/item/Supporter cards, with picks such as X Speed supporting the pivot from Moltres to Centiskorch once it's been powered up on your bench, Potion for keeping these Pokemon in play when needed, Giovanni to push for a single turn knockout on many opponents (including ex) by pushing Centiskorch's damage from 130 to 140, Sabrina to disrupt your opponent, and Poke Ball and Professor's Research to help you get the right cards in your hand, and into play
For more optimal decks for lower player counts, I would suggest using the fully playtested decks I posted previously
Trophy Hunter I really like the detailing on this one
The flexibility of this ability - and the fact that you can hit each one in a single turn in the right deck - means youll be generating absurd value constantly, just by playing other creatures or making creature tokens