Lucario Melmetal get's the energy out of your deck and into play
Zacian V does the same thing but turns into the beat stick when he has 3 energy on him
The metagross GX ability allows for you to spam those attacks that make you discard or that make it so that you can't attack with that pokemon next turn. Moreover; since you'll be discrading most if not all the energy attached to your main when retreating to get rid of negative effects; you can use max potions while dodging the down side of discarding all attached energy since meagross's ability reattaches energy from the discrad pile
Articuno V helps with getting the Zacian Vunion pices in the discard, when that's done, you can still use the ability for no penalty when paired with Mt Coronet
Zacian Vunion : Big "one shot anything" dogo
Basicaly: get 3 enrgy in play on Zacian V or 2 on Lucario&Melmetal - then get at least 2 metgross gx on bench - Max potion as needed - ??? - Profit