Played in decks that don't rely on the Extra Deck, like Eldlich
Ensuring all images are tap to zoom, making sure everything aligns nicely on mobile, having the entire page load in chunks so that it doesnt immediately eat all your data if youre not scrolling all the way to the bottom, those sort of things
However, I'd put $5 on Sylveon ex being the most powerful card from the set - it's Pokmon Pocket's first real draw engine, acting like a Professor Oak and drawing you two cards the turn you play it
To make your Pokmon card listings stronger, try adding clear photos, accurate condition notes, a good title, and competitive pricing based on recently sold listings
The downside is that you have to exile it at the beginning of your next end step, so it's a one-time deal