For example, if Warrior is the chosen creature type and you control Bramblewood Paragon, a Runeclaw Bear would enter the battlefield with an additional +1/+1 counter." Even these additional rulings don't add much complexity, and changing or adding Creature types to a card remains pretty straightforward
As for playability, Nissa, Steward of Elements is okay
Thematically, some of them have abilities that play well with other cats, like lifegain and +1/+1 counters, while other legendary cats are off doing their own thing
It truly is a rarity in of itself, that should be continued in each new expansion (so fans can chase after these cards that feature all of their favorite Legendary Pokmon)
A Pokmon ex, on the other hand, offers out two Prize cards as opposed to one when it is knocked out