Layout: GardEX is Set Up, Scream Tail & Espathra are primary attackers, Mimikyu & Flutter Mane are interference.
Use Professor's Research, Turo's Scenario, Explorer, Ultra Ball, & Moonlit Hill to discard any psychic energy in your hand.
Use Mimikyu & Flutter Mane to interfere with powerful attackers while you set this up
Use Arven to find & attach boosters to Screamtail (hp goes up to 150)
Use Gardevoir EX to add energy (& damage) to Screamtail to boost Roaring Scream (140 DMG = 280 DMG output)
Use Gardevoir EX to add energy to Espathra to do 30 x Energy Count DMG
If necessary use Porygon, Palossand, & Drampa as alternate attackers.