Fighter numbers are a method of identifying and sorting characters in Super Smash Bros. Ultimate.
As explained by Masahiro Sakurai, the numbers order characters based on "the order in which they joined the series". They are ordered in the following way:
- SSB (01-12): The starter characters are ordered by their placement on the character selection screen, which in turn is based on each character's first appearance (with Mario and Donkey Kong as the oldest and Pikachu as the newest). The unlockable characters are similar, though they are sorted column-first rather than row-first as the starters are; as such, Ness precedes Captain Falcon despite being created later. This also matches their series debut order, explaining why Ness comes before Captain Falcon.
- Melee (13-26): The starter characters are ordered by their first appearance on Melee's E3 2001 reveal trailer (based on which ones had their faces shown first, meaning that the Ice Climbers and Sheik come before Zelda, whose hand appeared earlier in the the trailer) and by extention, in Melee's opening movie. Zelda was the only character on Melee's starting roster who wasn’t revealed to be playable at E3 2001, which could also be the reason why Zelda is placed after Sheik, despite both Melee and Brawl treating her as the primary character and Sheik as an alternate form. The unlockable characters are ordered by how many Vs. Mode matches are required to unlock them, and thus Young Link, Ganondorf, Pichu, and Mewtwo's roles in the reveal trailer are ignored.
- Brawl (27-44): The characters first revealed in Brawl's original trailer are first (in the order they were revealed), followed by the remaining newcomers in the order revealed on the official website. Notably, Pokémon Trainer is not given a fighter number; instead, their three Pokémon (Squirtle, Ivysaur, and Charizard) are numbered, ordered by their cycling order.
- SSB4 (45-63) and Ultimate (64-82): The characters are ordered by when each newcomer was revealed. Pyra and Mythra are given separate numbers.
- Echo Fighters share their number with their "parent" in addition to an apostrophe (') stylistically referred to as "dash" in Japanese and Chinese or a superscript epsilon (ε) in other languages, regardless of which game they joined in. For example, Samus's fighter number is 04, while Dark Samus's fighter number is 04ε, despite Dark Samus making her playable debut in Ultimate.
The fighter numbers are used to order characters on Ultimate's character selection screen and promotional material. The Mii Fighters are the only fighters whose placement on the selection screen does not correspond with their numbers, as they are instead shown as the last characters on the selection screen, likely due to their customizable nature. The only major in-game usage of the fighter numbers is that Echo Fighters, due to not having their own fighter number, can be optionally stacked onto the character they are based on in the character selection screens for Vs. Mode, Special Smash (except for Smashdown), Tourney, and Online modes (except for Quickplay). The only place that the fighter numbers are explicitly shown in-game is on the Move List.
A similar system is used for ordering stages on Ultimate's selection screen, where all stages are ordered by when they first appeared in the series (with the exception of stages which debuted in and are shared between both versions of Super Smash Bros. 4, which are mixed in with stages that debuted exclusively in Super Smash Bros. for Wii U).
- Coincidentally, Greninja and Inkling have the same fighter numbers as their respective costume numbers in Super Mario Maker.
- Had Echo Fighters been numbered normally (i.e. not grouped with their base fighters), they could be placed accordingly:
- Dark Pit would have been either between Palutena and Pac-Man or between Shulk and Bowser Jr. Although he was officially revealed after the launch of Super Smash Bros. for Nintendo 3DS, his status as a playable character was teased directly after the reveal of Palutena.
- Lucina would have been between Pac-Man and Robin.
- Daisy would have been between Inkling and Ridley.
- Richter's position would have been unchanged, as he was revealed directly after his base fighter Simon and before Chrom, making him the only Echo Fighter with this trait.
- Chrom and Dark Samus would have been between Richter and King K. Rool, with Dark Samus listed after Chrom.
- Ken would have been between Isabelle and Incineroar.
- If Echo Fighters had been numbered normally, the final number would have been 89 instead of 82.
- Oddly, on the back of the North American physical case of Ultimate, several fighters are misplaced from their fighter number order:
- Luigi is between Jigglypuff and Peach, rather than between Pikachu and Ness.
- Zelda is between Young Link and Ganondorf, rather than between Sheik and Dr. Mario.
- Roy is between Pokémon Trainer and Diddy Kong, rather than between Mewtwo and Chrom.
- Ike is between Wii Fit Trainer and Rosalina & Luma, rather than between Snake and Pokémon Trainer.
- Toon Link is between Ken and Bayonetta, rather than between R.O.B. and Wolf.
- Palutena is between Ridley and Corrin, rather than between the Mii Fighters and Pac-Man.
- Cloud is between Corrin and Simon, rather than between Ken and Corrin.
- The Super Smash Bros. 4 Official Site and the character lineup that replaces the opening movie in Super Smash Bros. for Nintendo 3DS order the starting characters in a similar way. The major exceptions are that Zelda is ordered before Sheik in SSB4, the third-party characters and Miis are ordered after everyone else, and on the website Lucina (the only unlockable character who was revealed before launch) is ordered after Robin despite being revealed first. The lineup in for 3DS similarly orders the unlockable characters by their debuts, though with Duck Hunt before Bowser Jr. and the three clones ordered after the other unlockables.
- Although the amount of fighter numbers and the amount of playable characters differ due to Echo Fighters not counting for fighter numbers and transformation characters counting for multiple, competitively speaking the amount of characters counted on the tier list is identical to fighter numbers, despite the different criteria. Lucina, Chrom, and Ken are counted as separate characters due to their significant differences, adding three, while removing two out of three of Pokémon Trainer's Pokémon and either Pyra or Mythra subtracts the three from Lucina, Chrom, and Ken.
- Additionally, by sheer coincidence, Rosalina & Luma's fighter number and tier list position in the first Ultimate tier list are the same number.