Rattata as an baby Pokemon was given to Crystal from Maryelle and Louie, two farmers raising litters of baby Pokemon in the episode Baby Pokemon Theft as a thanks for protecting the litters of babies from Team Rocket. She made her debut as a major character in Crystal's New Rattata as an Rattata. Team Rocket attempted to steal Rattata telling Crystal that Rattata were rare in the Kalos region and were planning on taking her to the boss, but Crystal foiled their evil plan. In The Picnic, Rattata was seen eating lunch with the rest of the gang's Pokemon and a net fell on all of them and Team Rocket attempted to make off with the stolen Pokemon, but they were rescued by their trainers. In Crystal's Third Show, Crystal used her Rattata in her third showcase making it to the finals with Gabe and Erika. In the upcoming episode called Crystal Battles Aria, Crystal is set to battle Aria for the title of Kalos Queen, but she loses.
Rattata as an baby was taken care of by Maryelle and Louie along with the rest of the litters of baby Pokemon until they gave her to Crystal. Crystal took great care of Rattata and has become one of her loyal Pokemon.