Blissey and Jessie putting together the good luck charm
Sometime prior to Ignorance is Blissey, Jessie met a Blissey from Happy Town as a Chansey. She explains to James and Meowth that she had studied with the particular Chansey in a Pokémon Nurse School together, where they had become best friends. Jessie, unfortunately, did not qualify to become a nurse and quit the school, due to the fact that she is not a Pokémon, so she cannot learn the move Sing. Chansey had given part of the medal she had received as a nurse to Jessie so that they could remember each other.
Blissey made her first official appearance in Ignorance is Blissey. Ash and his friends had met up with Blissey in the Pokémon Center. Seeing that they were hungry, she prepared food for them but due to her over-enthusiasm, she spilled the food on them. A well-meaning yet clumsy Pokémon, the more Blissey tried to help, the more problems she caused. When Team Rocket tried to steal food from the center, Jessie met Blissey and they immediately recognized each other. Blissey then gave Team Rocket most of the food in the pantry. The others in the Pokémon Center soon found out and everyone blamed Blissey. Wanting to help her friend, Jessie pretended that she had tricked Blissey into giving them the food. She also faked attacking her to make Nurse Joy and the others believe her. They were soon thrown out, but not before Jessie whispered to her friend Blissey to keep it a secret.
Blissey first appered with Nurse Joy in Alola in SM004.
As shown in SM005, a Blissey which is used by Nurse Joy in a Pokémon Center on Melemele Island, oversaw Nurse Joy as she helped to heal an injured Popplio, which Lana had rescued from some Team Skull Grunts, who were harassing it.
Personality and characteristics
The Blissey from Happy Town was shown to be very clumsy, as seen when she fell after trying to give food to Ash and his friends. Similar to the other recurring Pokémon that Nurse Joy have, Blissey were shown to be very helpful.