The Nintendo Switch remaster of the game adds a new five-chapter storybook similar to what the first game had, which tells the story of two identical twin sister Lumas named Mari and Lu. In the events of this story, it's revealed that Lu would grow up to become Lubba, the captain of Starship Mario, which subsequently revealed that the character had been retconned to be female. Previously, Lubba's gender had not been consistent between the original game's localizations and other appearances, a discrepancy that was not widely known up until the release of the Switch version.

In the original Japanese release of the game, Lumas were not referred to with gendered pronouns, and in a developer interview published in the original game's Japanese guidebook, producer Yoshiaki Koizumi claimed to not know what Lubba's gender was, simultaneously referring to her with male pronouns and comparing her to a grandmother or aunt (depending on the translation) to the surprise of the interviewer. The original English, French, and Italian localizations designate Lubba as male, while the original Spanish and German localizations designate Lubba as female. In all versions of the game, she is voiced by a male voice actor, Scott Burns, and both the original English and Japanese websites for the game use male pronouns. Prima's English eGuide for the original game appears to avoid using pronouns for Lubba entirely.

This confusion extended to Lubba's trophy description in Super Smash Bros. for Wii U, in which the English release calls Lubba male, but the Japanese release does so while comparing the character to "an older lady from a working-class neighborhood."