I'm much more partial to the battle themes this time around. Of course, I think everything related to dank music goes to Team Skull. They took all the good ones with all that funk in their themes, especially in Guzma's encounter theme. Gladion's theme is so edgy, but it's almost like something out of a Sonic game, in both the encounter and battle themes. It doesn't detract from how much I like it though. Another battle theme I can't get over is Red and Blue's Battle Tree Theme. It's not just the epic 2016 remastering that enchants me, but every instrument that you hear as it progresses. The violins really drive home the fact that they're daunting trainers to challenge in the beginning, and the accordions kind of give a sense of nostalgia, like a feel of olden times, it's kind of like home to me. Not sure if it makes sense, but in the end the violins and accordions mixed kind of gives the impression of time moving forward, because not only did the graphics improve with time, but also how we compose music for games. It shows how far these two have come since the original games. The instruments at the end before it loops back to the beginning is what I really enjoy the most about it.
Of all my favorite themes unrelated to trainer battles, it definitely goes to Vs. Solgaleo/Lunala/Necrozma and Vast Poni Canyon. The synth in the former really gives the "powerful cosmic entity" feel for the legendaries, and then (what I believe to be) the electric guitar highlights their legendary power. The wind instruments in Vast Poni Canyon captures the adventurous feel to it, since it's a very wide area, so the theme really gives you the thought of wanting to explore every corner of it. I will say though, the wind instruments in the beginning greatly remind me of the flutes from the Steamboat Willie theme from Mickey Mania, though not in the same lighthearted, jovial one as that theme.