This isnt feasible in real life scenarios, such as situations where you have someone breathing across from you
The set was originally teased on February 27 (Pokmon Day) in a brief, very vague aside during the lackluster Pokmon Presents
IIRC in Yugioh there is only a certain number of Blue-Eyes (from the show?), so you could put a rule on the card 'there may only be X Blue-Eyes on the battlefield at any time', Star Wars CCG used to have permanents that you could have 2 or 3 copies of in play, in addition to stuff you could only have 1 of, the concept would work fine here too, only this could care about both players' boards
In the Pokmon Trading Card Game, new sets become legal for tournament play on the second Friday following the sets release
I know that Ashling the Pilgrim plus 99 Mountains is a fun meme, but it's just so meh otherwise
Creating three tokens for 3 mana is going to be good and will trigger a lot of the other cards in your deck nicely