While we've already heard some of his music in the game, as suspected - it seems more of it was featured in the most recent Pokémon presents. Toby confirmed in a new series of tweets that he composed the music for the Terastal Raid battles in the game.
What's perhaps most interesting though is the story behind this. When the game's director gave Fox his "assignment", he showed him a picture of Lucario with a giant oversized flower as a starting point, and told the Undertale creator this was the "new game mechanic" (the Terastal Phenomenon).
From there, Toby was left to create a song out of it. Here's his own interpretation of everything using one of his trademark illustrations:
What do you think of Toby Fox's latest Pokémon track? Have you pre-ordered one of the new games yet? Leave a comment down below.