This Starly is a normal/ -type Pokémon owned by Mitsumi.
Mitsumi only used her Starly when an Onix went into rampage and Hareta decided to stop it. Hareta grabbed Onix' head and then, Mitsumi called her Starly in order to help him. Although at the end, Starly didn't really help at all, it was only flying nearby the scene.
None of Starly's moves are known.