I know that this entire shrinking shenanigans is overtalked to death but i have one, crucial point to make. Besides Pokemon, we also frequently see Pokeballs being used to store items and it's not some rare mechanic - literally every non-hidden item in overworld is held in a balls. Is a potion, evolution stone, TMs or even other balls having an ability to shrink itself? Because that's fucking retarded and makes no sense.
Pokemon having ability to shrink themselves is the most retarded retcon ever and deny A MAJOR MECHANIC that exist literally from the start of this franchise, go figure out.