No confirmation thus far but it's likely to be similar to M20 with the majority of its music being remixes, though I would be surprised if there was absolutely no original content in there somewhere. The CDs are likely being released together in a similar manner to the Let's Go OST. Have the newer versions and the original tracks together for the sake of comparing differences between similar tracks/scenes
Several Johto tracks were remixed for the anime and movies over the years, most of them starting in 1999.
Listening to that track reminded me of the instance I had been thinking of - it plays at the end of Happinas the Happy Nurse/Ignorance is Blissey when Happinas is mournfully thinking of Musashi after she's been blasted off
Such a wonderful bit of music... (I love both the Ecruteak and Cianwood versions in HGSS, I can't help just wandering around those two towns whenever I am in proximity in the game just to indulge in the music!!)
Toofoolery.
Ever since XY, the earliest tracks being used in the show are from Movie 15 and its associated Pikachu Short, anything else beforehand has been left out (However the XY series remixed many tracks from BW, M12 and 14 which are still in use today). No music from before that point has been in use. There's no official reason as to why this is the case, though theories go as far as the tracks in rotation being more associated with the buyout by Sony Music, or as simple as a creative choice to not use older recordings. There's just no clear cut explanation. That being said, various Movie 20 tracks HAVE been in use during SM since late 2018, though most of them aren't the OS remixes that people are most familiar with (but even those popped up during Brock and Misty's Alola visit).
