Meloetta
Meloetta is a small feminine humanoid Pokémon with long, green hair and is one of the few Pokémon to have alternate forms. Its default form is Aria Forme, but it can also transform into Pirouette Forme, where its long green hair forms into a compact red beehive hairstyle and its body seems to take on more of a ballerina's form. It changes forms whenever it uses its unique move Relic Song. Meloetta appears in a short film that accompanied Kyurem vs. the Swords of Justice in Japanese theaters, entitled Meloetta's Moonlight Serenade. The same Meloetta is a main character in the Best Wishes! Season 2 anime, joining Satoshi, Iris, Dent, and Hikari in their journeys through Eastern Unova. (source: Bulbapedia)