There have been some fringe archetypes created with Solgaleo-GX as a driving force, such as Russell Laparres Tyranitar-GX/Solgaleo-GX and Michael Catrons Solgaleo-GX/Blaziken-GX (expanded) decks
"Most of that doesn't really add too much value, versus the ones that are rare and hard to find." Still, some special card designs can be very valuable, like the Van Gogh-inspired Pikachu, which was discontinued in 2023 by an Amsterdam art museum amid the frenzy it sparked among fans
So long as a card was printed at common at any point, it is legal in the format (excluding acorn-stamped, illegal, and banned cards)
In decks capable of generating a lot of mana through rituals for example, this sounds very fun and powerful
PSA 10 premiums justify $20-40 grading costs for these specific cards
Shadowless cards were printed right after 1st Edition and before the common Unlimited run, so they sit in the scarce middle tier