Alternate costume (SSBM)

Super Smash Bros. Melee used the X and Y buttons on the Gamecube controller to change costumes. Because of this, there were no limits on how many costumes a player can choose from (unlike SSB's limited four C-buttons).

Bowser

Bowser's alternate costumes in SSBM

Green (default)
Red: Resembles a Spiny or red Koopa Troopa. It also resembles Roy Koopa's early in-game sprites without the sunglasses. On the CSP, he has a red eye. In Melee, this eye is blue.
Blue: Came from Bowser's international artwork for Super Mario Bros. It also looks like Iggy Koopa's early in-game sprites.
Black

Captain Falcon

Captain Falcon's alternate costumes in SSBM

Dark Blue (default)
Black: Possibly came from the Japanese commercial for F-Zero X.
Red: Based on Falcon's rival, Blood Falcon's outfit, even altering the logo on his back to say "Blood Falcon." In the Japanese beta of Melee, it read "Hell Hawk" instead. [1]
White: Based on the colors of Jody Summer's outfit, commonly known as "Captain Fabulous".
Green: Based on the colors of Pico's outfit.
Blue: Possibly based on his artwork from the original F-Zero.

Donkey Kong

Donkey Kong's alternate costumes in SSBM

Brown (default)
Black: It was in the "Monkey Smash" mode in Donkey Kong 64.
Red: Based on DK's sprite in Donkey Kong.
Blue: One of the alternate colors from Donkey Kong 64.
Green: One of the alternate colors from Donkey Kong 64.

Dr. Mario

Dr. Mario's alternate costumes in SSBM

White: (default) Despite wearing white pants in his own game, Dr. Mario wears indigo jeans in Melee.
Black: Based on the Game Boy Dr. Mario from GB Dr. Mario.
Green
Blue: Possibly based on the blue scrubs and purple nitrile gloves worn by modern doctors.
Red: Perhaps based on Nurse Toadstool's color scheme.

Falco

Falco's alternate costumes in SSBM

White (default)
Red
Blue
Green: Assumed to be what Falco wore when he was not a member of the Star Fox team.

Fox

Fox's alternate costumes in SSBM

White (default)
Red: Based on his costume on the Japanese Star Fox box art.
Blue
Green: Possibly modeled after his father, James McCloud.

Ganondorf

Ganondorf's alternate costumes in SSBM

Brown (default)
Red: Possibly represents one of Ganondorf's beast form's attire.
Blue
Green
Purple

Ice Climbers

The Ice Climbers' alternate costumes in SSBM

As can be seen in the image, the Ice Climbers' orange and red costumes will place Nana in the lead, making Popo follow.

Blue (default)
Green
Orange
Red

Jigglypuff

Jigglypuff's alternate costumes in SSBM

Pink (default)
Red
Blue: Similar to the bows from the original Super Smash Bros.
Green
Yellow: This palette swap is that of a crown with the exact same design as Peach's.

Kirby

Kirby's alternate costumes in SSBM

Pink (default)
Yellow: This color swap is Keeby, who was Kirby's companion in games that featured co-op mode. It is also the same as when he is Beam Kirby or Needle Kirby, without the hat. It was also an alternative palette for Kirby in the multiplayer for Kirby 64.
Blue: The same as when he is Ice Kirby, without the hat. It was also an alternative palette for Kirby in the multiplayer for Kirby 64.
Red: The same as when he is Fire Kirby, without the hat.
Green: Likely a homage to his days on the green Game Boy screen. It was also an alternative palette for Kirby in the multiplayer for Kirby 64 and the skin tone for Plasma Kirby.
White: A reference to his monochrome appearance from the original Kirby's Dream Land for Game Boy. It is also similar to the colors of Kirby's depiction on the North American box cover of Kirby's Dream Land.

Link

Link's alternate costumes in SSBM

Green (default)
Red: Based on the the Goron Tunic from The Legend of Zelda: Ocarina of Time.
Blue: Based on the the Zora Tunic from The Legend of Zelda: Ocarina of Time.
Black: A homage to Dark Link. However, unlike the Brawl version, only his tunic is altered.
White: Resembles the use of the Blue Ring in The Legend of Zelda.

Luigi

Luigi's alternate costumes in SSBM

Green (default)
White: A reference to Luigi's appearance in Mario Bros. and Super Mario Bros.
Blue: Resembles the artwork for Mario on the cover for the NES version of Mario Bros., though that's not what he wore in the actual game.
Pink: Comes from the game Wrecking Crew, in which Luigi wears pink.

Used when Luigi is on the Red team.

Mario

Mario's alternate costumes in SSBM

Red (default)
Yellow: Based on Wario, the same as his previous yellow costume.
Blue: A red/blue reversal of his traditional colors and these are the colors he wore in his first appearance in the game Donkey Kong. This is seen as a partial reference to Mario's varying appearances in games prior to Nintendo's officially establishment of Mario's outfit of consisting of a red shirt, blue overalls and red hat. In various earlier games, Mario occasionally also appeared with sometimes a blue hat, red shirt with blue overalls or a red hat, blue shirt with red overalls. Interestingly however, Mario never appeared in any game with the particular combination of a blue hat, blue shirt, with red overalls as it appears here, but this color scheme does resemble the Balloon Fighter.
Brown (Black): A reference to Foreman Spike from Wrecking Crew '98.
Green: A color inverse of his traditional colors. Contrary to popular belief it is not a reference to Luigi, however it does coincidentally resemble Luigi's colors from the arcade version of Mario Bros.

Marth

Marth's alternate costumes in SSBM

Blue (default)
Red: The only costume in Melee to change the color of his tiara.
Green: Possibly based on the standard color for NPC units in Fire Emblem.
Black
White: Based on Leaf, the protagonist of Fire Emblem: Thracia 776.

Mewtwo

Mewtwo's alternate costumes in SSBM

Purple (default)
Orange: Used as an Easter egg in Pokémon Stadium.

Used when Mewtwo is on the Red team.

Blue: Resembles Mewtwo's in-game sprite colors for Pokémon Red & Blue. Also used as an Easter egg in Pokémon Stadium.
Green: Mewtwo's "shiny" color.

Mr. Game & Watch

Mr. Game & Watch's alternate costumes in SSBM

Mr. Game & Watch's costumes may come from the colored LCD screens used for some of his games.

Black (default)
Red
Blue
Green

Ness

Ness's alternate costumes in SSBM

Red (default)
Yellow: The yellow/black color scheme resembles that of the Hanshin Tigers, a Japanese baseball team.
Blue: Is based off of Ness's younger self that he encounters briefly in EarthBound, who was wearing a blue hat. Some also consider this outfit to be a reference to EarthBound's final battle against Giygas, where a reflection of Ness's face appeared in the Devil's Machine. However, contrary to popular belief, the reflection was not wearing a different hat than the real Ness.
Green

Peach

Peach's alternate costumes in SSBM

Pink (default)

Used when Peach is on the Red team.

Yellow (Orange): This costume changes nearly Peach's entire appearance to that of Daisy, including her hair color, earrings, dress style, gloves, crown, and even Daisy's old skin color (in later games following Melee, Daisy's skin color was bleached significantly).
Blue (Purple)
- For some reason, Peach's blue palette swap is recognized by Melee as purple, much unlike other blue palette swaps.
White (Gray): Represents how she appeared in her first appearance in Super Mario Bros, without the red hair. She also uniquely wears pantyhose with this costume.
Green

Pichu

Pichu's alternate costumes in SSBM

Yellow (default)
Red
Blue: Gives Pichu goggles similar to the "Swimmer" class of the Pokémon series. Despite Pichu not returning for Brawl, Pikachu's blue costume in that game is based off of these same goggles.
Green: Gives Pichu a backpack similar to the one worn by Pokémon Trainers throughout the Pokémon series.

Pikachu

Pikachu's alternate costumes in SSBM

Yellow (default)
Red: Has Pikachu wearing the hat of Red, the protagonist of the original Pokémon installment. The fur color is based on a "shiny" Pikachu.
Blue: A party hat similar to the one from the original Super Smash Bros.
Green

Roy

Roy's alternate costumes in SSBM

Purple (default)
Red: Based on the "enemy" unit color in the Fire Emblem series.
Blue: Based on the "player" unit color in the Fire Emblem series. Is the only palette to change Roy's golden highlight color (to silver).
Green: Based on the "other" unit color in the Fire Emblem series.
Yellow: Based on the "partner" unit color in the Fire Emblem series; while the color didn't show up until Fire Emblem: Path of Radiance in 2004, the game was in the making during the time Melee was released.

Samus

Samus's alternate costumes in SSBM

Orange (default)

Used when Samus is on the Red team.

Pink: Based off the appearance of the Varia Suit when missiles are selected in the original NES Metroid game.
Black
Green:
Purple: Based on the Gravity Suit.

Used when Samus is on the Blue team.

Sheik

File:Sheik colors.jpg

Sheik's alternate costumes in SSBM

Medium blue

Switching back to Zelda using this palette swap will have her dressed in pink.

Red
Blue
Green
White

Yoshi

Yoshi's alternate costumes in SSBM

All of Yoshi's costumes appear as different variations of the Yoshi species in many of his games, such as Yoshi's Story and Super Mario World.

Green (default)
Yellow: Based on the stomping Yoshi in Super Mario World.
Cyan (Light Blue)
Red: Based on the fire breathing Yoshi in Super Mario World.
Blue: Based on the flying Yoshi in Super Mario World.
Pink

Young Link

Young Link's alternate costumes in SSBM

All of Young Link's colors are exactly the same as Link's, except ordered differently.

Green (default)
Red
Blue
White
Black

Zelda

Zelda's alternate costumes in SSBM

Pink (default): Resembles Zelda's appearance in The Legend of Zelda: Ocarina of Time.

Transforming into Sheik using this palette swap will have her dressed in medium blue.

Red: Resembles Zelda's first appearance in The Legend of Zelda if Link possesses the red ring.
Blue: Resembles Zelda's first appearance in The Legend of Zelda if Link possesses the blue ring but not the red ring.
Green: Resembles Zelda's first appearance in The Legend of Zelda if Link possesses neither the blue ring nor the red ring.
Lavender (White): Resembles Zelda's appearance in The Legend of Zelda: A Link to the Past.

Stats

There is a total of 123 palette swaps.
The average number of costumes per character is 4.731
Captain Falcon, Kirby and Yoshi share the highest amount of color swaps: 6.
There are 10 fighters with 4 color swaps, and 13 with 5.