Cute! I love these types of topics!
Name: Swirl Ball
2ffect: 3x catch rate against 'dancing' Pokémon such as Bellossom, Spinda, and Oricorio among others, as well as Pokémon that can learn dance-type moves (Quiver Dance, Petal Dance, etc). When one of these Pokémon is captured with the Swirl Ball, they will learn a new move called Swirly Dance.
Design: Cream-colored ball with a red swirl on it, referencing Spinda's colors.
How to obtain: Win every contest rank with a Pokémon that has at least one dance-related move to unlock it in the Mart.
Ignore the fact that not all dance moves have the same/dance-related name in the original Japanese pls. :D;