Michele Knotz modified her performance as Misty a bit, because she doesn't sound too much like she did in the previous episode. Bill Rogers stayed the same, though, and he still sounded great. Honestly, if I were watching this at a younger age, I'd never know Eric Stuart was replaced.
As this is the season finale, this'll be the last time the laid-back greatness that is "Under the Alolan Sun" will be heard. Gotta say, I'll miss it. As for the rest of the soundtrack, it's great as usual. Important episodes like this tend to get the most meticulous musical attention. The only misstep was them keeping whatever theme that was when Sophocles and Lillie's battle against Brock started. Another one of those "mountain out of a hill" (no, not a molehill, because this situation was a bit too serious to be called a mere molehill; still, the point stands) Mima-isms. But other than that, the music (both the dub-exclusive music and the kept JP stuff (and I never thought I'd accept a use of an XY battle theme)) was great.
Battle, battle, battle. That's all this episode was, and it was a lot of fun. A great way to end the season. Now the wait for season 21 begins.
So how was the season in general? Well, I think we all know what its Japanese self drove me to, particularly its 21st episode (damn that one to Hell), but its dubbed self kept up the tradition of fixing the show to the point where it's an enjoyable Saturday morning cartoon. The acting from everyone but Lana, the writing apart from just a few gaffes and Samson Oak's awful puns (even though they're meant to be awful), and the music basically everywhere were all great this season. Now on the show's own merits, there were some boring episodes (the Oranguru one being the lowest point of the season if you ask me), lots of fun episodes, and some very heartfelt ones ("One Journey Ends, Another Begins..." being the highest point of this season if you ask me). Oh, and the animation's amazing. Just thought I'd say that, too. I don't know why it's being seen as a huge problem.
Best of luck to Season 21!