This attack's damage isn't affected by Weakness, Resistance, Pok-Powers, Pok-Bodies, or any other effects on that Pokmon.
So I would keep Empoleon on the bench until the benches are pretty much full, then you can put Empoleon into the active Pokemon spot and use Attack Command which will be more effective early on since more Pokemon are in play, but as soon as you start knocking out your opponent's Pokemon you'll be able to do less and less damage with Attack Command, just make sure you have a full bench at all times when Empoleon is in the active Pokemon spot
This foundational knowledge helps you utilize your deck effectively
This card, without all the bells and whistles, functions as a board wipe on a creature
And whoever draws a card, they have to attach a card from their hand to this one as an XYZ material