Ok, I was just planning on throwing together a deck with the new Castform from Hp and I realised rather awkwardly hes a basic. I kinda knew this before, but it dawned on me, if by some chance I get stuck with no basic pokemon in my hand, I would be forced to play him. He's not something I would Like to be stuck with at any point. So I'm guessing that may be why he's only an uncommon.