Pokémon - Season 7 Episode 2

The heroes spot a pair of Pokémon bowing to one another, as dance partners would, and begin flying around one another in a wide circle. Brock identifies them for what they are (Volbeat and Illumise), prompting May and Ash to pull out their Pokédexes: May's identifies Illumise, and Ash's Volbeat. The two Firefly Pokémon are still dancing about. While watching, a Nurse Joy greets the group, asking of they are here for the May Festival, for the dance performance of Illumise and Volbeat. She notes that it is almost time for the practice runs, and indicated two people standing out on the lake's pier, saying they are Volbeat and Illumise's Trainers, Romeo and Juliet.