Unused content (SSBB)
Masahiro Sakurai himself stated that there were several more characters planned to be included in Brawl, but were cut due to time constraints, though he could not divulge which characters specifically were cut. Both leftover data in Brawl's code and interviews conducted after its release have been partial indications on the identities of these characters.
Discovered in Brawl's files
Multiple unused character data files were found in the disc. Sometimes colloquially referred to as "The Forbidden Seven", they consist of (in the order in which they appear in the game's files):
As the files themselves are empty, the filenames are the sole indication of their identities. Despite this, it can be argued that there is little ambiguity over them:
The inclusion of the character files led to the formation of a rumor that was later proven false.
Within Brawl's game data, many unused and empty music files have been found on the disc. The reason that they were removed is unknown, though it is commonly believed that some tracks were removed due to copyright issues, limited space, or simply personal preference by the developers.
All track files in this list are "empty"; that is, they do not produce any sound when played back. Much like the unused character files in the game, this leaves only the filename to determine what the music track was intended to be. However, the more equivocal filenames make it more difficult to determine the specific cut tracks.
It should be noted that the songs in this section, as all the songs used in the final product, follow a chronological trend.
Along with the above music files, the following unused songs were also found in the data, intended for use in the Subspace Emissary:
The files could either have been background music (mainly because there few tracks that are exclusive to the Subspace Emissary), or as fanfares. It is unknown what they were meant to be used for.
Among the unused music files are various victory themes that are specifically attributed to one character, suggesting that characters were supposed to have their own victory theme independent of their series. However, they are completely empty. In the final product, only Meta Knight has a different fanfare than other characters of his universe; Super Smash Bros. 4 would eventually add alternative fanfares to more characters like Dark Pit, Bowser (in addition to Bowser Jr.) and Rosalina & Luma. Ultimate adds additional victory themes for Corrin, all Fire Emblem Awakening characters, Byleth, all Metroid villians, and Sephiroth; Piranha Plant also gains Bowser and Bowser Jr.'s victory theme.
Of note is that two of these unused fanfares, snd_bgm_Z38_FMYU2 and snd_bgm_Z39_FROY, refer to two unused character files in the game, those characters being Mewtwo and Roy respectively. Strangely, Wolf is missing an unused fanfare despite being from a returning series, likely due to his late inclusion. The files are as follows:
Along with this, there are two other unused fanfares, snd_bgm_Z52_JCLEAR1 and snd_bgm_Z53_JCLEAR2. Their intended use is unknown, though it is believed they could have been used as stage clear themes.
Some characters have unused trophies with "R2" in the filename, showing them in various poses (most in possible gameplay poses, some not). It is possible that these were intended to be a third trophy for each character, similar to how every character in Melee has three trophies, and the concept was scrapped for an unknown reason. Some trophies are carried over from Melee. Most of them don't have the white part of the eyes. Out of all of the R2 trophies, Only 15 can be hacked by replacing the R1 trophies to the game. For unknown reason, Pikachu freezes the game if viewed.
The game's effects files show names for enemies initially planned to appear in the Subspace Emissary:
Only seven of those enemies were dubbed in the English version. Those are:
"Allian" could have been either entirely unique alien-like creatures, or an early name for the Primids.