Even with the combo potential in mind, the Nightmare Creature can get out of hand if your graveyard is big enough
Charizard cards always have high value compared to others given the fiery lizard is a fan-favorite Pokemon, but when you add in the fact that this is a unique black-and-red shiny version, the card becomes exponentially more sought-after
It also has the potential to be the biggest eldrazi, caring about not just cards exiled with its own abilities, but from anywhere, making it paltry to get plenty of +1/+1 counters on it without casting
It can also be reconfigured into an equipment and attached to another creature with trample or other evasion to give them the same benefit
As a card that can grab any basic Pokemon from the deck, it makes finding V cards - which are considered basics - trivial, and will add consistency to decks looking to embrace the new cards that are coming to the game
They're niche cards, so nobody else at the table will be interested in taking them