Tera Mewtwo ex

Mewtwo ex is horrible, I won’t lie to you by saying it's actually a sleeper. Gaining energy on the bench is made easier with Xatu; however, Mewtwo EX does such low damage. That’s why we play Gravity Mountain and a Maximum belt to reduce its energy KO requirement in certain matchups (Charizard, Dragapult/stage 3 decks). Overall, it’s a slow card to set up, and its recovery isn’t great either. The only good thing about it is the steamroll if your opponent isn’t able to

Mewtwo ex is horrible, I won’t lie to you by saying it's actually a sleeper. Gaining energy on the bench is made easier with Xatu; however, Mewtwo EX does such low damage. That’s why we play Gravity Mountain and a Maximum belt to reduce its energy KO requirement in certain matchups (Charizard, Dragapult/stage 3 decks). Overall, it’s a slow card to set up, and its recovery isn’t great either. The only good thing about it is the steamroll if your opponent isn’t able to set up (though that’s least likely).

Pokemon
Greninja, Fez, Xatu, Mew - used to draw, looking for energy or recovery options (can use fez or mew to attack aswell)
Mewtwo ex - your main attacker
Enamorus - used to defend/recover energy
latias - Retreat without discarding energy/ can also attack
Cleffa - your main starter 

THIS IS A GOING SECOND DECK
turn one (your turn) you should prioritize Cleffa in your Active zone, it sets up for xatu search and mewtwo ex requirement.

A common combo
Arven -> nestball/poffin(for natu) and pick up Rescue Board. nestball/poffin -> bench Cleffa; Rescue Board Active pokemon -> retreat for cleffa to Active; 
then just use Cleffa's move Twinkling Hope for 2 energy

Trainers
Arven - A combo starter/GOAT (board setup and attack setup)
IONO - Stall/Reshuffle (for horrible hands)
Bosses Orders - Attacking
Tulip - Recovery
Heavy ball - for cleffa if needed
Nest/Poffin - for setup 
Ultraball - for xatu
Gravity mountain - for zard and other stage 3 decks
Forest Seal Stone - Can search anything (starter/attacker/recoverer)
Switch - cleffa/postioning
Maximum belt - reduce energy KO requirement
Powerglass - recovery
Rescue Board - cleffa/positioning
12 Basic Psychic energy

Hopes n Dreams
Overall, I really wish Mewtwo EX didn't require pure psychic energy for the photon kinesis requirement. It could have used the Crispin/electric generator for support.