|This article is written from the Real Life point of view|
VS. Zazabi, Barrier Core-X (VS.ザザビー、 バリアコアX) is the upbeat, MIDI-style boss theme of both Zazabi and the Barrier Core-X in Metroid Fusion. The theme was composed by Minako Hamano and Akira Fujiwara. A portion of it is included in the orchestral medley, "Metroid Fusion Arranged Version", on the Metroid Prime & Fusion Original Soundtracks.
The theme can be heard here.