The basic play mechanics of Pokmon TCG are just like the video games, as two pokmon face off in turn-based battles
I imagine that itll play like a slightly watered down version of Winota, Joiner of Forces, which isnt a bad thing
They're trash cards on their own and I have yet to see anyone else play with them, but they have an interesting interaction with one card in particular that is heavily played in Commander: Nearly every Commander deck that runs black will run Urborg, Tomb of Yawgmoth, either for mana fixing and/or for its synergy with Cabal Coffers
Like most Magic: The Gathering cards, the value of The Companion of the Wilds depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Unknown Event)
Bonus points for the snappy flavour text: Id say its still a fair fightnow my friend is about the size of your ego. -Mr Witherbloom, probably 1