The Ruby part of this deck includes the very handy Sumerian Talisman (that allows the player to draw a card every time one of their characters is banished in a challenge) and 2 copies of Dragon Fire to banish any opponent character you may struggle to deal with
(Like the Gym sets, this set has great Trainers, Supporters, and Stadiums for decks running cards from this set and the original Rocket set like Dark Vileplume.) EX Deoxys Meteor Falls This Stadium allows any active Pokmon to use any move from its previous evolutions
Genesis Impact Booster Box
While this is just a silly Green creature, if you're able to attack with the Hydra more than once without it being killed, you're likely winning the game thanks to trample
I think there is a corresponding risk and compatibility with his Deck, but personally, I like this card because it is less direct and numerically stressful than the Crystal Beast + Bridge (In some cases, Grave) set