AboutNurse Joy is not a single entity. Rather, there are many Joys working as nurses across the various regions of the Pokémon world.
As a rule, Nurse Joys are kind, earnest, honest Pokémon nurses who take care of sick and injured Pokémon, but will confront a Pokémon Trainer if they are not properly caring for their Pokémon.
They are not entirely identical, though aside from themselves, it seems that Brock is the only one who can tell them apart. However, each Nurse Joy will have a different color cross on her hat that indicates which location she works at.
Supposedly, they are all extremely similar-looking relatives—cousins, sisters, etc. However, fans have proposed various other theories has been suggested for the strange phenomenon—everything from time travel, to cloning, to the Nurse Joys being Pokémon themselves. emotion_bigheart