DJ Rotom
DJ Rotom is a Rotom that has chosen to inhabit a miniature stereo system, and has no apparent plans to leave it. They keep a collection of CDs — physical media, which in the context of a semi-abandoned island feels both anachronistic and oddly touching — and mix them into sets that play continuously across whatever part of the island they're currently parked in.
Music as Environment
In a game about environmental restoration, DJ Rotom occupies an interesting niche: they restore the sonic environment. An island without Pokémon is quiet. An island coming back to life has birdsong, wind through grass, the background hum of creatures going about their days. Rotom's music sits alongside all of that, neither replacing it nor competing with it.
Players have noted that the music Rotom plays seems to shift depending on the state of the surrounding area. Sparse, early-game zones get quieter, more atmospheric tracks. More fully restored areas get something livelier. Whether this is intentional curation on Rotom's part or the game's ambient music system is, charmingly, unclear.
Species Notes
Rotom is a Ghost/Electric-type that can inhabit and take the form of various appliances — a refrigerator, a lawnmower, a washing machine. The stereo/DJ form is Pokopia-specific, tailored to this character. It's among the more inventive applications of Rotom's established lore in any Pokémon game.