From Bulbapedia, the community-driven Pokémon encyclopedia.
For the character in Pokémon X and Y whose French name is Millie, see Emma.
Millie (Japanese: ミリ Millie) is a character of the day who appeared in Unfair Weather Friends.
Millie was a new employee at the Weather Institute near Fortree City. What Bart and the other scientists at the Institute didn't know was that the person they thought was Millie was actually Brodie, an agent from Team Magma who was undercover to steal ancient Pokémon data.
After Brodie escaped with the data, the real Millie showed up at the Institute. At first, everybody was cautious and wondering why Brodie had returned. However, Brock was convinced that it was indeed the real Millie, as he had fallen in love with her, but not Brodie in disguise. Soon after, Bart quickly put Millie to work, having her type up all of the ancient Pokémon data from the Institute's hard copies into the computer system.
She was mentioned by Max in The Ribbon Cup Caper.