These Volbeat are a group of bug-type Pokémon owned by Romeo.
Romeo was training his Volbeat for the festival, where they would dance with Illumise during the night. However, Romeo failed a lot of times, causing the Volbeat to fall in their training. The heroes managed to secure them and bring them to the shore. Later, Romeo admitted he and Volbeat were doing fine until Juliet comes to them with her Illumise. Hearing Juliet's Illumise got captured, everyone went after Team Rocket. Once they have been found, Romeo's Volbeat have been captured by Team Rocket, until their leader, Beat, crashed the machine. The Volbeat used Signal Beam, which blasted Team Rocket away. During the night, when the festival took place, the Volbeat used Tail Glow during their performance, which dazzled the audience.