Gholdengo ex 550 damage for 1 energy

Gholdengo's ability lets you draw one if on the bench, two in active, which is great card advantage. But that's not all! Its only attack costs 1 metal energy and can do up to 550 damage (by discarding the remaining 11 metal energy in the deck).

The support cast is made up of:

Lady - which lets you search for four energy

Superior Energy Retrieval - which lets you set up again after an attack

Adaman - which can discard your extra metal energy to tutor two cards (i.e. Super Energy Retrieval to get energy back and something else pending situation)

Lumineon - to find your Lady and Adaman

Arceus Vstar - as a backup attacker and tutor

Squawkabilly and Bibarel - to refresh your hand

And a general unoptimized stew of pokeballs, supporters, and other items.