From Bulbapedia, the community-driven Pokémon encyclopedia.
My Music (Japanese: オレ曲 My Tunes) is a feature in Super Smash Bros. Brawl and Super Smash Bros. for Wii U that allows the player to change the chance of each song used for the music in each stage. There are 288 background music tracks in Brawl, 13 of which are from the Pokémon franchise. In Super Smash Bros. for Wii U, there are 507 music tracks, 23 of which are from the Pokémon franchise. Most must be unlocked by finding CDs during gameplay, which randomly appear or are dropped by Mew when released from a Poké Ball.
List of Pokémon music
Super Smash Bros. Brawl
Super Smash Bros. for Wii U