I really wanted to arrange a "winter-y" song, and this song has always stood out to me. It's in 6/8 and has really pretty bassline movement. When you hear it, you'll probably think of a lot of other songs that it sounds similar - it's one of those songs that really doesn't sound like it's from a video game at all.
It's composed by Shota Kageyama, who started with Pokemon by doing a lot of the track arrangement work for HeartGold and Soul Silver, and then was kept on board for composition/arrangement starting with Gen 5. I'm a big fan of both his composition and arrangement work, so I wanted to make sure to mention him!