Haven’t really seen anyone mention it here but just in case there's anyone who actually believes that the Sinnoh Gym Leader soundtrack used in Pikachu VS Hala’s Hariyama means something, it doesn't. It's just a track from movie 17 (Diancie), any soundtrack that was available for XY can be used in SM as well. The track was also heard in XY, but only once (Hawlucha beating Mega Absol), the reason it was used so rarely is because the version used in the movie only fits very specific scenes, namely ones that are meant to be short, like the Absol KO or the quick start of Pikachu VS Hariyama before the episode hit the commercial break (in the movie it played in the introduction, where we only see a glimpse of Diantha VS Wikstrom, so yeah it just kinda fades out). They do not have a full length version of the song that they could use for proper hype moments included in the SM soundtrack. If we ever do hear a proper version, then you can speculate about DP remakes lol.
And when I say available I don't mean they literally can't use older music, they just clearly aren't going to, starting from BW they've had this trend of only using music from a specific pool, namely movie music that wasn't used in the previous series yet (movies 12 and 13 are DP movies but their soundtracks were saved for BW instead of being used in DP, same thing for movies 15 and 16 being used for XY instead of BW. I’m pretty sure older series did this too though but it’s less noticeable cause AG and DP never dropped any old tracks), in XY's case remixed versions of BW tracks, and in SM's case straight up XY tracks. This is probably done for the sake of convenience, it'd obviously take more time to choose from 20 years' worth of music than just 3 or so. Though it could also be so that each new series would have a stronger sense of identity, which would align with the lesser continuity in the story itself (which also started in BW so yeah).
