Typically the most expensive Pokemon cards are ones from years past that have printing defects, were only obtainable at special events, and/or were only printed in small quantities, so what ultimately makes this shiny Charizard-GX so exciting for collectors is that its out in the wild right now
[-8] You get an emblem with Whenever a creature dies, return it to the battlefield under your control at the beginning of the next end step. Lifelink Whenever another nontoken creature you control dies, exile Liliana, Heretical Healer, then return her to the battlefield transformed under her owner's control
Nevertheless, Brimaz, King of Oreskos is definitely a cat to include in your deck, just potentially not as your commander
Aethersquall Ancient Aethersquall Ancient is a leviathan that finds homes in energy decks, and pretty much nowhere else