We're working with a single printing of every card, so even though Grizzly Bears has been printed 26 times across various sets, we only really care about one of them
And so in August 2022, I made a spreadsheet checklist of every Porygon, Porygon2, and Porygon-Z card in the history of the English Pokmon TCG, and I started my hunt from almost nothing
Other cards like Jhoira, Weatherlight Captain might offer more consistent value in a similar deck, but The First Doctor could still see play in a more casual or thematic setting for Doctor Who fans
Stupid development
Additional ways to clue you in to some special, often valuable cards: Secret rares have a collector number higher than the total # of cards (supposedly) printed in that set, for instance "65/64" or "110/105." Secret rares can range anywhere from a couple of dollars to hundreds of dollars