Putting this all together, we can establish the following facts: A Magic card does not need to feature the traditional Magic card back in order to be tournament-legal, as long as the cards are played in an opaque sleeve
Drawing cards in Pokemon (or any card game for that matter) is seldom ever a bad thing
Mewtwo GX (Shiny Vault, Hidden Fates) Hidden Fates is one of the most beloved and consistently valuable special sets in the history of the modern Pokemon TCG, and its Shiny Vault subset has produced some of the most enduringly sought-after cards of the entire Sun and Moon era
Adding 20 cards to your deck seems like a massive drawback that would hamper the consistency of your deck yet Yorion got the ban hammer in several formats, and some Modern decks still tinker with 80 cards, even without the extra creature in their sideboard
Many creature tokens are small 1/1s without abilities, making them perfect for sacrificing in combat to stop your attacks
Each have the collector number and set code of their original printing