From Bulbapedia, the community-driven Pokémon encyclopedia.
The Pokémon Chronicles theme is the second opening and ending theme produced for Pokémon Chronicles, which was first used in the U.S. Cartoon Network airing of part 2 of The Legend of Thunder!. This is the first and, so far, only English opening theme to have no lyrics.
This theme aired as an opening only with the American televised airings of Pokémon Chronicles. The Toonami Jetstream and European airings instead used the opening theme based on Pokérap GS.