Pokemon TCG has a legality code printed on the card in the same corner as the rarity and set symbol and artist and collector number. Their version of Standard is defined as "all cards with codes E, F, or G" or whatever they're currently on at the moment:
They've only had it for five years but it certainly seems to be working for them and it was intuitive to me when I briefly played that game because it mostly correlated with Standard rotations (they'll print E for a year, then F for a year, etc etc). Of course, they also reprinted old cards more often, so people were used to looking for the symbol and playing older versions that lacked it, idk if that'd work as well with Magic's lower reprint rate, who knows.
Didn’t know that. The idea came to me in a dream
