Honestly, for Elio I've always envisioned that his custom battle theme or insert song is rap-themed. Something like from Samurai Champloo, Afro Samurai, certain ones from Death Battle (Thanos vs Darkseid, Miles vs Static, or even Jin vs Ryu), or that one song by Wu-Tang Clan that plays during the dream fight between Huey and the Blind ***** Samurai from the Boondocks.