DevoidLight
Gym Leader
I'm suggesting an option to choose the music that the other player will hear when you battle them in PVP, and maybe an encounter theme as well. You could only chose songs from battles that you have won, so you would need a badge to use the Gym Leader theme from a region, be champion to use the region's champion theme, and so on. Perhaps it could be selected from a menu on the Pokegear radio screen?