Although naturally each and every Special Move in the series mirrors itself and its hitboxes, an odd exception is made for Cloud's Cross Slash. When Cloud does the move, he draws the Kanji "凶" ("Kyo"), which means misfortune, bad luck, evil, and other negative things, and because this is a kanji it must be written a certain way regardless of orientation. It cannot simply be flipped like other moves, meaning that the move's hitboxes change depending on where Cloud is facing. From the right side and facing left, Cross Slash will actually hit lower, making it better at hitting smaller characters. However, from the left side facing right, Cross Slash will hit higher up, making it a better anti-air attack. This also occurs with the Limit Break version of the move. These differences makes Cloud mirror matches uniquely imbalanced and not as 50/50 as they would be for other fighters.

Pikachu and Pichu's Neutral Special, Thunder Jolt, is actually a move taken from and exclusive to the Pokémon Trading Card Game, specifically the Pikachu Card from the very first Base Set. This is true for both the English and Japanese versions of the move, as the same exact name in both languages is used from the card (Thunder Jolt and "Electricity Attack" respectively). This makes Thunder Jolt the only adapted Pokémon Special Move to be directly taken from the TCG, instead of the games or anime.

In a 1999 interview with game's director and designer Masahiro Sakurai published in Nice Games magazine vol.3, he was asked if Super Smash Bros. appealed to a younger age group? He responded:

Snake's match victory theme ironically is based off of the Game Over jingle from Metal Gear Solid.

In an interview with Xander Mobus, who voices the Announcer in Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate, he revealed that Nintendo, in an effort to stop character leaks, would often throw him off about which characters would be in the game or DLC by giving him "red herrings", otherwise they would give him some ridiculous names to say that would be far-fetched. He even claimed that because of the intensity of this, he didn't believe that the Duck Hunt dog and duck were in the Nintendo 3DS and Wii U versions of the game as playable characters, and assumed Nintendo was referring to the Duck Hunt cartridge being in the game instead, and thus believed it to be a fake.

While he is normally an avid gamer, Masahiro Sakurai revealed in a Famitsu interview that he strictly refrains from sharing what he is currently playing on social media sites because of fears it would be misinterpreted by the Smash Bros. fandom (especially outside of Japan) as a confirmation of a new fighter for the series. He also states that the issue has gotten so bad that he frequently declines appearances on TV shows that deal with a specific game for the same reason.

Giga Bowser's design was inspired by Sakurai's vision of how Bowser looked before Super Mario 64.

"The old Bowser was scary. In the NES era, characters were more symbolic, so you had room to use your imagination. When I looked at the original Bowser, I saw a frenzied, terrifying monster.

But, advancements in technology have allowed designers to convey characters in greater detail, and in recent games his image has steadily become cuter.

Naturally, this is a current game, so it needs to use his current design. And from there, Giga Bowser (unexpectedly?) happened to come into existence."

The Poison Mushroom in the Super Smash Bros. games is the only item borrowed from another series whose appearance does not stay true to its original franchise. In the Mario series, poison mushrooms have distinct colouring from other mushrooms, but in the Super Smash Bros. series, they look similar to Super Mushrooms in order to purposefully confuse players. The differences between the two items are nearly unnoticeable - the Poison Mushrooms are only slightly less red and have a meaner look.

In each game the texture for Ness's yoyo includes the year of the game's release:
• "2001" for Super Smash Bros. Melee
• "2008" for Super Smash Bros. Brawl
• "2014" for Super Smash Bros. for Nintendo 3DS and Wii U
• "2018" for Super Smash Bros. Ultimate

Pit's hammer swinging animation is meant to resemble how he moves around and attacks with a hammer in Kid Icarus and Kid Icarus: Myths and Monsters.

In the Super Smash Bros. series, Yoshi is usually one of cast's heavier fighters. He even outweighs Samus and Ganondorf in the PAL versions of Super Smash Bros. Melee and is on par with Wario in Super Smash Bros. Brawl. Despite this, Yoshi is usually labelled as a lightweight or middleweight character in the Mario Kart and Mario Tennis spin-offs.

Like the actual Pikmin series, blue Pikmin are the only variety of Olimar's Pikmin that can swim in water. If any other of Olimar's Pikmin go in water, they will die instantly.

In German versions of the Super Smash Bros. games, Popo had his name changed to "Pepe" because the word "popo" means "butt" in German.

In the November 2014 issue of GameInformer, it was revealed that Masahiro Sakurai takes photos of a pose-able action figure to create the moves for new characters whenever one is being made. The image shown is the action figure poses used to make the Mii Fighters' moveset.

When performing Bayonetta's forward throw Tetsuzanko, she'll occasionally say "Juu'nen Hayain Dayo!" which in English translates to "You're Ten Years Too Early!".

This is a reference to one of the the win quotes of Akira Yuki from the Virtua Fighter series in which the Tetsuzanko is also one of Akira's signature moves. This move was also possible in Bayonetta.

Bowser Jr. takes less damage from any attacks that hit his clown car and not his body.

Masahiro Sakurai wanted Geno to appear as a playable fighter, as he also wanted to include him previously in Brawl, and thought the character felt suited for the series since he has a gun for a hand. However, in the end he wasn't included, but instead appearing as a Mii Costume.

One of the longest works of literature in the English language is a Super Smash Bros fan fiction. At 4,047,350 words, it's about 8.5 times the length of the Lord of the Rings books.

Ryu is the first playable character in the Super Smash Bros. series to have two different final smashes.

Jigglypuff is the only character in the series to be instantly K.Oed when its shield breaks.

When using Pac-Man's Up taunt, the Namco Roulette taunt, various characters from other Namco games will appear:

• Clovis from Dragon Buster
• Don from Taiko no Tatsujin
• Fighter from Bosconian
• Fighter from Galaga
• Galaxip from Galaxian
• Ghost from Pac-Man
• Gilgamesh from The Tower of Druaga
• King from King & Balloon
• Mappy from Mappy
• My Car from Rally-X
• Paccet from Baraduke
• Pooka from Dig Dug
• Red Baron from Sky Kid
• Secret Fighter from Gaplus
• Solvalou from Xevious
• Topcup from Libble Rabble
• Andor Genesis from Xevious
• Valkyrie from Valkyrie no Densetsu
• Runner from Metro-Cross

Throughout the series, Kirby can transform into a pink block with eyes from the SNES game, Panel De Pon (Known as Tetris Attack Internationally).

In each iteration, Fox's voice has been provided by the same voice actor who played him in the most recent Star Fox game.

N64 - Shinobu Satochi - Star Fox 64 (Japanese Voice Actor)
Melee - Steve Malpass - Star Fox Adventures
Brawl - Jim Walker - Star Fox: Assault
Wii U/3DS - Mike West - Star Fox 64 3D
Ultimate - Mike West - Star Fox Zero

Shulk and Pac-Man are the only characters in the entire Smash Bros. series to not have a green palette swap option.

Mentioning Project M, the name of an unofficial modified version of Super Smash Bros. Brawl to reintroduce elements from Super Smash Bros. Melee, by name on any of Nintendo's Miiverse channels will trigger an automatic ban for discussing "criminal activity".

Series creator, Masahiro Sakurai, has stated that both Super Smash Bros. Melee and Super Smash Bros. Brawl were developed with the mindset that there were to be no more sequels after them.

Mega Man's alternate color swaps are all taken from possible weapon colors used in previous Mega Man games:
• Red and White - Rush Coil from Mega Man 3
• Green and White - Leaf Shield from Mega Man 2
• Gold and Brown - Metal Blade from Mega Man 2
• Blue and White - Air Shooter from Mega Man 2
• Green and Yellow - Slash Claw from Mega Man 7
• Red and Black - Flame Blast from Mega Man 6
• Yellow and Black - Top Spin from Mega Man 3

Captain Falcon is the only character in the Super Smash Bros. series whose availability status has changed with each sequel, being unlockable in both the original Super Smash Bros. and Super Smash Bros. Brawl, but available from the start in Super Smash Bros. Melee and Super Smash Bros. for Nintendo 3DS and Wii U.

Some of Meta Knight's palette swaps in Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate resemble other characters from the Kirby series.
• His Pink palette is designed to resemble Kirby.
• His Purple palette resembles Galacta Knight's appearance in Super Super Star Ultra's "Meta Knightmare Ultra" mode.
• His Grey palette resembles Dark Meta Knight.

Domestic and international popularity polls are used when deciding who to add into a Super Smash Brothers game. After that, certain questions such as whether a character can present something interesting and whether they're a good representative of their series are asked.

Charizard's purple alternate color in Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate is possibly a reference to his shiny sprite in Pokemon Gold and Silver. Including purple skin, a grey-white belly and dull green wings.

When Mega Man gets KO'd, his KO explosion has blue spheres coming out from where he was KO'd. Mega Man is the only character in the series to have a unique KO explosion, and is a reference to his death animation from the Mega Man series of games.

Mega Man's up-tilt, the Mega Upper, is from his Marvel vs. Capcom moveset. However, it originated from Mega Man 2: The Power Fighters.

Donkey Kong's audience cheer in Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate is a reference to the DK Rap from Donkey Kong 64 in chant form.

When frequently using Little Mac's taunts, there's a slight chance that Doc Louis can be heard giving some advice. Each taunt has a unique sound clip.

Mario's blue and pink alternate outfit is based on his appearance in the original Mario Bros. arcade game.

One of Princess Zelda's alternate outfits in Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS and Wii U is the same as the design used in Super Smash Bros. Melee, based on her appearance in The Legend of Zelda: Ocarina of Time.

Two of Zero Suit Samus' alternate costumes in Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate are based off of the perfect ending in Metroid: Zero Mission.

One of Little Mac's alternate costumes in Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate is a reference to the Punch-Out!! arcade game, where he was represented by a translucent array of green lines.

One of Little Mac's palette swaps in Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate is based on his appearance in Super Punch-Out!!.

In Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate, Kirby's dark blue alternate color with yellow eyes is designed after Meta Knight's appearance without a mask. This is based on Meta Knight's appearance after being defeated in Kirby's Adventure.

One of Mario's costumes in Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate is the patriotic Mario skin from NES Open Tournament Golf released in 1991.

One of Luigi's alternate costumes is based on his appearance in the Japan-only movie, Super Mario Bros.: Peach-hime Kyushutsu Dai Sakusen!.

When Kirby takes Zelda's ability, he wears the headdress Zelda wears as a child in Ocarina of Time, despite the fact Zelda is an adult in Super Smash Bros and the headdress appears nowhere else in the game.

Super Smash Bros. Ultimate updates this appearance to use Zelda's hair instead.

Since Super Smash Bros. Brawl, Wario is the only character in the series to have a 4th taunt. It is activated by pushing any of the taunt buttons while he is riding the Wario Bike.

In the Japanese versions of Super Smash Bros and Super Smash Bros: Melee, the Beam Sword sounded similar to a Lightsaber from the Star Wars series. This was changed during localization for other regions. In Super Smash Bros: Brawl, the sound effects have been kept the same for all versions.

When selecting the Famicom and NES color schemes for R.O.B., the stickers on their base change to reflect their real-life counterparts. The decal for the Japanese Famicom R.O.B. reads "Family Computer Robot", while the decal for the North American NES R.O.B. reads "Robotic Operating Buddy".

In Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate, these regional color schemes based on R.O.B.'s original models for the Famicom and NES are made his default palette depending on if you are playing the Japanese or International versions of the games respectively.

It's possible that the blue outfit for R.O.B. is based on his cameo as Nav-Com in Star-Tropics for the NES.

In all of Captain Falcon's appearances within the Super Smash Bros. series, his red color swap is actually the outfit of Blood Falcon, his evil clone in the F-Zero games, complete with the correct insignia.

Aside from Pikachu and Jigglypuff (whose costume accessories change from game to game), Samus is the only character to have one of her team-based costumes change between games: In the original Smash Bros. and Melee, Samus wears her default (orange) costume when she is on the red team, but in Brawl, her pink costume is used instead. This could be due to the fact that in her Zero Suit, her default costume color is blue. So they needed to give her a new costume that would depict both forms in something closely resembling Red.

Pikachu is the only playable Pokémon in the Super Smash Bros. series to have a visible gender difference in the Pokémon series. Male Pikachus look like the one in Smash Bros, but females have a small indent in their tail, which vaguely looks like a heart. However, gender differences in Pokémon were introduced in Generation IV, which came out after the first Super Smash Bros. and Melee.

Female variants were later included in Super Smash Bros. Ultimate.

Pokémon Trainer is the only character that has a custom name in their original series to not be given a default name in Brawl, and is instead given a generic name. It is clear from the character design that the suitable default name would be "Red" as he is named as such in Pokémon Gold and Silver, and again in the remakes which were released after Brawl. The reason this was done is unknown.

Kirby uses a different dash attack in each of the first three Super Smash Bros. games. In the original Super Smash Bros., he performs a slide tackle. In Melee, he performs "Burning Kirby" (an ability seen in some Kirby games, and merged with the Fire ability in others), while in Brawl, he performs Yo-Yo Kirby's "Break Spin" from Kirby Super Star.

Pikachu is the only character in the entire Super Smash Bros series to only have four costume color options in the first three games.

The following fighters are the only characters in the Smash series to appear in another fighting game:

•Snake appeared in Dream-Mix TV World Fighters as a playable character.
•Mega Man has appeared in the Mega Man Power Battle series, a few Capcom VS games (mainly the Marvel vs. Capcom series) and Street Fighter X Tekken (in his "Bad Box Art" form).
•Donkey Kong also appeared in Punch-Out!! for Wii as a boss.
•Sonic appeared as a playable character in Sonic the Fighters and Sonic Battle.
•Link appeared in the GameCube version of SoulCalibur II.
•Little Mac appears in Punch-Out!!.
•Ryu is a main character from the Street Fighter series.
•Cloud appears as a playable character in the Dissidia Final Fantasy series.
•Terry is a main character from The King of Fighters series.
•The Kirby series has its own set of spin-off fighting games called Kirby Fighters.
•Charizard, Lucario, Mewtwo and Pikachu appear in the fighting game Pokken Tournament.

In SSB and Melee the first syllable of "Samus" is pronounced /sɑ/ ("saw"). However, in Brawl, it's pronounced /sæ/ ("sah"). This change in pronunciation is consistent with the way Samus is pronounced in Metroid Prime 3: Corruption.

Jigglypuff's eyes are blue in the Pokemon series, but green in the Super Smash Bros. series, the same color as a shiny Jigglypuff.

In all of her Smash Bros. appearances, Peach is depicted with a ring on her middle finger, which is absent in other games.

Snake's alternate palette swaps in Super Smash Bros. Brawl and Super Smash Bros. Ultimate are based on wearable camouflage outfits in Metal Gear Solid 3, such as the Fire camo and Spirit camo.

All lines spoken by Marth in Melee/Brawl/Wii U and 3DS are in Japanese. These are what they all are translated:

Marth's taunt - "Everyone, please watch me!" ("みんな、見ていてくれ！")
Marth's counter - "There!" ("そこだ！"), "I won't let you!" ("させるものか！")
Marth's victory poses - "This time, victory is mine, right?" ("今回は僕の勝ちだね。"), "Today, too, I managed to survive." ("今日も生き延びることが出来た。"), "There's no way I can lose!" ("僕は負ける訳には行かないんだ。")

He also has an unused sound file in the Debug Menu of the game which is "Let's Dance!" ("レッツダンス！")

Mario's Cape attack can be used on a taunting character to make them face the other way in ways that are otherwise impossible, like making Wario face the screen while doing his side taunt.

Peach's Final Smash since Super Smash Bros. Brawl is a piece of music from Super Mario Bros 3 that has been sped up. The music is from World 5: The Sky, Coin Heaven bonus levels and in the Warp Zone.