this card is banned because people would play it at tournaments and claim it was their birthday and judges got tired of having to check if they were lying
Its common for trainers exploring hard to reach places to leave gifts for other trainers, as a little “You found this place too!” (Think of it like geocaches)
Items like potions, antidotes or TMs are common, as they could help a trainer in need.
And how do they keep these items safe from the elements?
By putting those items in pokeballs, of course!