While it is not known to evolve into or from any Pokémon, it has a second Forme activated by using the move Relic Song in battle. Its original Forme, Aria Forme, will then become the Normal / Fighting-type Pirouette Forme.
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Meloetta seems to be a femininely anthropomorphic figure with musical bar-style streaks in its hair, quarter notes (crotchets) (♩) for its arms and hands and pupil-less eyes resembling whole notes (semibreves). It has a jewel on its forehead and a black headpiece that seems to be shaped like a treble clef which doubles as an attached microphone such as one often used by singers. Its ovular head seems to be ⅓ its body's height and about half its height in width. In its Aria Forme, it has light blue eyes and flowing, wavy hair with light-blue ovals that resemble whole notes. In its Pirouette Forme, it has auburn hair that seems to be stylized in a high bun and red eyes. In either Forme, its midriff and eyes match its hair. It is a genderless species.
According to artists in Unova, Meloetta's beautiful music and dance inspired many works of art, music, and songs. This made the Pokémon popular among both musicians and dancers.
Meloetta is able to change forms when it uses the move Relic Song, which changes its form from Aria Forme to its Pirouette Forme, or vice versa. In its Aria Forme, Meloetta can sing beautiful songs. While in its Pirouette Forme, Meloetta can perform graceful dances. In its Aria Forme, it is a dual-type Normal/Psychic-type Pokémon; in its Pirouette Forme, it is a dual-type Normal/Fighting-type Pokémon. It reverts to Aria Forme when switched out or when the battle ends. Like many other Legendary and Mythical Pokémon, Meloetta is capable of becoming invisible.