The Super Smash Bros. Ultimate Twitter account is referencing the secret battle with Culex from Super Mario RPG: Legend of the Seven Stars.
The Final Fantasy series is often credited with introducing the concept of a “Superboss”, which is an optional enemy that is stronger than the final boss in the story. The first Final Fantasy Superboss was Warmech, but the most famous Superbosses in the series are Emerald and Ruby Weapon from Final Fantasy 7. Square Enix has also used Superbosses in its other games, like the Dragon Quest series.
Sephiroth is now available in Super Smash Bros. Ultimate, following the reveal of the “Sephiroth Challenge” during the recent mini-Direct hosted by Masahiro Sakurai. The hopes of Geno fans around the world were dashed during this Direct when Geno returned as a Mii costume and not a playable character. Sakurai has at least thrown the Geno fans of the world a small bone, as a screenshot uploaded to the official Super Smash Bros. Ultimate Twitter account references one of the most famous moments in Super Mario RPG: Legend of the Seven Stars.
The screenshot shows Bowser, Mario, and a Geno Mii Fighter facing Sephiroth’s Final Smash, where he transforms into Safer-Sephiroth from Final Fantasy 7. This moment references the battle against Culex, the Superboss from Super Mario RPG: Legend of the Seven Stars. Culex isn’t meant to be a specific character, rather, he is an allusion to the entire Final Fantasy series itself. Culex has a bizarre design that is reminiscent of an angel, he fights alongside four elemental crystals, and he uses music from the Final Fantasy series as his theme.
The Geno fans of the world were devastated to learn that he was relegated to being a Mii Fighter costume again. The fact that his costume wasn’t included in the base version of Super Smash Bros. Ultimate meant that fans could hold on to hope that he would make it into the game, but that wasn’t meant to be. The screenshot on the Super Smash Bros. Ultimate Twitter page is a sad glimpse at what could have been.