They are more-so relics of the pokemon industry, rather than true cards, printed on cardstock
You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast them
Hope that helped, and I hope that soon ill see your designs circulating around the commmunity
Instead of Cocoon, try Forced Adaptation, which puts a +1/+1 counter on the enchanted creature each turn without a drawback, or Spider Umbra, which gives your creature +1/+1 and reach, plus is a Totem Armor
You can find more of my Magic musings on Twitter/X @travishall456 and on Bluesky:
This long-awaited return to Kamigawa wouldnt be happening if players hadnt been asking about it all this time, and Im sure a lot of those requests came from Ninja fans