I'm pretty sure it was used in the Sinnoh anime/movies since I haven't seen M17 and still recognized the particular arrangement

It's actually a remix from Movie 17 (the Diancie movie) the track is called Diantha vs Wikistrom. But yeah it's a remix of the DP Gym Battle theme :)

Yup, was pleasantly surprised by the little cameo. Sinnoh gym leader music is probably my favourite one of the 7 right now.

[Here is the Gym Leader's theme.](https://www.youtube.com/watch?v=qiCpFkybzeI)

Before the commercial break during Pikachu and Hariyama's battle, the music sounded awfully familiar. I decided to check it out and it was Gen IV's gym battle music. It's pretty neat :)

Edit: I can't post a video link of the episode, but I posted in hopes someone else noticed!


[Spoilers] Today's Pokemon Sun & Moon Episode used DP's Gym Leader BG Music