In the Japanese version's commentary with the game's composer Hitoshi Sakimoto, he stated that the "Random Waltz" theme was his very first battle theme he wrote, and it served as something like a test for different sampling techniques he wanted to experiment with, which he found very memorable. He also stated that, at the time of this interview, when he thought back on when he wrote the theme, it felt like it was 5 years ago, but it was actually only half a year.
Contributed by ProtoSnake