Bahamut ZERO (バハムート零式, Bahamut Type-0) is a summon from the Final Fantasy series.
Bahamut, as well as his various versions, is a commonly appearing summon in the Final Fantasy series. His first appearance was in the very first Final Fantasy, where he optionally granted the Warriors of Light (the playable characters) a class upgrade in exchange for a rat tail found in the Castle of Ordeals.
With Final Fantasy III introducing the Summon ability, Bahamut became available as the most powerful summon-able monster. His signature attack is Mega Flare, which deals heavy non-elemental damage to all targets. Final Fantasy VII introduced two new Bahamut variants, Neo Bahamut and Bahamut ZERO, which use even more powerful attacks named Giga Flare and Tera Flare respectively.
As a stage element
Bahamut ZERO appears as one of the summons on Midgar. When it appears, it attacks with Tera Flare, a flare that destroys the background and creates a continuously damaging pillar of light on the stage.
As a stage element
Bahamut ZERO reprises its role as a summon on Midgar, with no changes to how it functions.
As a spirit
Despite being featured prominently on Midgar, Bahamut ZERO did not receive a spirit in the base game of Ultimate. With the release of Challenger Pack 8, which focused on elements from Final Fantasy VII, it would be featured as the Legend-class spirit on Sephiroth's Spirit Board. Unlike the other summons featured as spirits, which use their artwork from Final Fantasy VII Remake (in which he did not appear in that form), Bahamut ZERO uses its appearance from the Midgar stage for its own spirit. The Spirit Battle occurs on Midgar against a giant Ridley with his color scheme based off Meta Ridley. Ridley is able to suddenly gain his Final Smash, Plasma Scream, after sustaining high damage, with the move acting as a direct reference to Tera Flare. Like other Legend-class spirits featured on the DLC fighters' Spirit Boards, Bahamut ZERO's spirit gives a unique ability, in this case an increase to Final Smash power.