Get Hisuian Basculin out front, and use Gather the Crew to get a Radiant Steelix, and another Basculin. Next turn, use it again for a Groudon and a Kyogre, while charging up Radiant Steelix. Hang on to at least one Klara and hopefully an energy recycler in your hand (and have training court in play) and then use Radiant Steelix's Destructive Finish attack (if you can't get Steelix with Gather the Crew use Hisuian Heavy Ball) to annihilate your deck and deal loads of damage.
Then, use Klara to get Hisuian Basculegion out of your discard pile and into your hand, and put it onto H. Basculin and Upstream Spirits attack--which has no energy cost--to do more damage and refill your deck with pure energy.
Next turn, you have two options:
Groudon's Magma Volcano attack for 400 damage
OR
Kyogre's Aqua Storm attack for 250 damage to 2 of your opponent's benched Pokémon.
When the deck gets low, use Hisuian Basculegion's Upstream Spirits attack again.
Shauna and the Ultra&Quick balls (quick balls will be changed to Nest Balls when ScVi comes out) are useful early game, and Training Court makes sure you have energy later on. The Switch Carts work on Kyogre, Groudon, and Radiant Steelix, and Hisuian Basculegion only had a retreat cost or 1 and is used less often, allowing you to switch between Pokémon more quickly. Energy Recylcer to put energy back into the deck without Hisuian Basculegion.
Thank you to Dmdrax and Jaeden for the helpful tips!