Nurse Joy's Chansey works at the Pokémon Centers in many regions of the Pokémon World to help injured Pokémon recover from their ailments. Nurse Joy's Chansey's are generally happy and helpful Pokémon and do exactly what Nurse Joy asks them to do. They learn their healing skills along side Nurse Joy as they both become good partners. They wear a nurse's hat but can become very angry and aggressive if its lost or taken from them as they are quite attached to it.
While Chansey may seem like a weak Pokémon due to its general happy state, it makes sure that the Pokémon Centers run smoothly by helping out in as many aspects as they can. They are also effective in helping protect the Pokémon Centers from intruders like Team Rocket.