F.L.U.D.D.

The Flash Liquidizer Ultra Dousing Device, abbreviated and better known as FLUDD or F.L.U.D.D., is a multipurpose water pack from Super Mario Sunshine invented by Professor Elvin Gadd, indicated by the Gadd Science, Incorporated logo at the base of its nozzle exclusively during the cutscene at Pinna Park. However, this is the only time FLUDD is shown to have it present. It features a water tank, two handles, and four interchangeable nozzles. In Super Mario Sunshine only, F.L.U.D.D. is also shown to have an artificial intelligence and is able to communicate with Mario and any other characters by speaking through the nozzle. F.L.U.D.D.'s name is a play on the word "flood," meaning "a large mass of water that often causes chaos in a public area."

Super Mario Sunshine
In Super Mario Sunshine, FLUDD can be used by Mario to spray water at objects or enemies by pressing. By doing this, Mario is able to perform a multitude of tasks, ranging from enhancing his acrobatics to cleaning goop off of various surfaces. FLUDD can switch between the Squirt Nozzle and either the Hover, Rocket, or Turbo Nozzle (depending on which one Mario currently has equipped) with. As the player continues to spray water with FLUDD, the amount of water in its tank will gradually get lower. When its tank is completely empty, the player must enter a body of water and hold the button, or collect a Water Bottle before any water can be sprayed again. Throughout the game, FLUDD will also often give the player advice on how best to complete a certain task or challenge via a HUD message, which varies depending on the situation.

Mario first encounters FLUDD on the ground of the Delfino Airstrip. When he walks over to FLUDD, it introduces itself to Mario before he puts it on; the player is then shown a tutorial video detailing how to use it. From this point on, Mario carries FLUDD around on his back and has access to it throughout the rest of the game. However, there are certain situations in the game when FLUDD will be unavailable to the player. For example, it is taken by Shadow Mario every time Mario enters a secret level that has not been cleared at least once. It is also taken by Shadow Mario in Episode 3 of Pianta Village, though in this case the mission involves finding a way around the burning goop that covers the entire village and retrieving FLUDD.

After Mario defeats both Bowser and Bowser Jr. in Corona Mountain at the end of the game, Mario and Princess Peach fall through the air and land on a small island on the west side of Delfino Plaza. After Mario regains consciousness from the fall, he notices FLUDD is not strapped to his back. When he locates FLUDD laying on the ground a few feet from him, it is shown to be damaged and malfunctioning (presumably as a result of Mario ground pounding various weak-points on Bowser and Bowser Jr.'s hot tub, as when it reached three weak points destroyed it began to stutter), asking Mario if "[it] was of assistance" before it shuts down completely. Shortly after, at Sirena Beach, several of the Toads accompanying Mario and Peach to the island present to them FLUDD, who has been fixed.

Several discrepancies occur in the Super Mario 3D All-Stars version of the game. In FLUDD's tutorial video, FLUDD simply says "button" instead of "R button". This is because when using normal controls, spraying is done by both and, and the subtitles have been changed to reflect this. Prior to version 1.1.0, the zoom-out effect when using the Turbo Nozzle underwater was not adjusted to fit the new widescreen display.

Super Mario Galaxy / Super Mario Galaxy 2
Although F.L.U.D.D. itself does not appear in Super Mario Galaxy or its sequel, Water Shooters, Fire Pressures, and Electric Pressures, all of which resemble F.L.U.D.D.'s head, appear.

Super Mario-kun
FLUDD also appears in the Super Mario Sunshine arc of Super Mario-kun. As with FLUDD in the games, it assists Mario, although it expresses more emotion and is more difficult to be with. It sprays Mario's face, causing him to yell at it, for example.

Mario Power Tennis
Several FLUDD-like water pumps appear in Mario Power Tennis; these heads are used to clear away the goop that can accumulate in the Delfino Plaza Court. Also, in the minigame Tic-Tac-Glow, the player must use balls of water shot by several FLUDD pumps to clear away goop in a tic-tac-toe like the game.

They also appear in the Chain-Chomp Challenge, when a Chain Chomp begins chasing a player. Its purpose is to calm the Chain Chomp down when it is enraged.

WarioWare series
FLUDD makes a small appearance in WarioWare: Smooth Moves in a microgame, in which it must be used to put out a building fire. The microgame later reappears in WarioWare Gold, where F.L.U.D.D. is instead used to clean graffiti off the side of the building.

Mario Kart Arcade GP series
While F.L.U.D.D. itself does not appear in the series, the Pump item found in Mario Kart Arcade GP 2 and Mario Kart Arcade GP DX is based on F.L.U.D.D.

Super Smash Bros. series
F.L.U.D.D. appears as Mario's down special move as of Super Smash Bros. Brawl, while the Mario Tornado from Super Smash Bros. and Super Smash Bros. Melee has been repurposed as Mario's down aerial move.

Super Smash Bros. Brawl
When Mario uses the move, he will put F.L.U.D.D. on his back and douse his enemies with water. The attack does not damage opponents, but instead pushes them. F.L.U.D.D. charges when the move is activated and shoots water when the button is pressed again, a longer charge resulting in a more powerful stream of water. F.L.U.D.D. stops charging when it is fully charged, allowing Mario to use it at a later time. Mario can also shield or roll to stop the charging. He can destroy projectiles with F.L.U.D.D., and the stream of water can be angled.

F.L.U.D.D. also appears as a trophy, obtainable when it appears at random in one of the game's single-player modes.

Super Smash Bros. for Nintendo 3DS / Super Smash Bros. for Wii U
F.L.U.D.D. returns in Super Smash Bros. for Nintendo 3DS and Super Smash Bros. for Wii U as Mario's down special move. In addition to having a shorter charge time, its water stream's strength, speed and range are each noticeably higher. When spraying water, F.L.U.D.D.'s nozzle is next to Mario's head on the right-hand side, while Mario holding a handle with his left hand and holding the nozzle with a right hand. However, in Super Mario Sunshine, F.L.U.D.D.'s nozzle is above Mario's head, with Mario gripping both handles with both hands.

Like other special moves, F.L.U.D.D. has two custom variations. The first is Scalding F.L.U.D.D., which sprays a short-range stream of water that deals fiery damage to opponents. The second is High-Pressure F.L.U.D.D., which sprays a more powerful stream of water and has greater range but also pushes Mario back.

In Super Smash Bros. for Wii U, F.L.U.D.D. is also featured as a collectible trophy. To unlock it, the player has to clear the Crazy Orders mode with Mario in twenty or more turns.

Super Smash Bros. Ultimate
F.L.U.D.D. once again returns in Super Smash Bros. Ultimate as Mario's down special move. In addition to retaining the improvements it received in Super Smash Bros. for Nintendo 3DS and Super Smash Bros. for Wii U, F.L.U.D.D. has less ending lag and an even stronger water stream. F.L.U.D.D. is also present as an Advanced-class support spirit that requires two support slots to use and grants immunity to sticky floors. The spirit can be purchased from Timmy and Tommy's shop for 1,000 Spirit Points at regular price.

Other appearances
In Minecraft's Super Mario Mash-up, the Bucket item is replaced by F.L.U.D.D. It can thus be used to carry water, lava or milk. In addition, Mario with F.L.U.D.D. on his back appears as a playable skin.

Nozzles
In Super Mario Sunshine, FLUDD is able to use a total of four different nozzles, only two of which can be equipped at one time. Upon starting the game, the Squirt Nozzle and the Hover Nozzle are equipped by default. The remaining two nozzles (the Rocket Nozzle and the Turbo Nozzle) can be equipped by breaking open various nozzle boxes located in Delfino Plaza and its surrounding areas (although not all nozzles can be found in certain levels). When equipping either of the remaining nozzles, the Hover Nozzle is replaced by the new nozzle, as one of the equipped nozzles must always be the Squirt Nozzle; the next nozzle that is equipped replaces the previous nozzle. To change between nozzles equipped, the player must press the button. Every nozzle is controlled with.

During development of Super Mario Sunshine, FLUDD was planned to feature a water gun nozzle, but the idea was scrapped due to controversy in the United States at the time.
 * Squirt Nozzle - The basic nozzle, which allows Mario to spray water at objects or enemies. If the button is held down lightly, Mario can run while squirting in the direction he is facing. If  is held all the way down, Mario stops and squirts in place while the player can use the analog stick to aim. In the Super Mario 3D All-Stars version, if the player is using a Joy-Con or a Nintendo Switch Pro-Controller,  squirts while running and  squirts in place allowing aiming. This is the only nozzle that can also be used when in over-the-shoulder mode.  This nozzle is equipped by default when starting the game or entering a level. When pressing  before spraying with FLUDD, Mario can spray water in large range in front of him, easier to clean large range of enemies or goop. It should be noticed that the large-range spraying cost large amounts of water each time. When rotating the  before spraying with FLUDD, Mario can do a spin attack that sprays water in all directions near him. The spin spraying can be combined with  to perform a spinning spray jump.
 * Hover Nozzle - This nozzle allows Mario to hover in the air for about 4 seconds, with slowly increasing altitude while in effect. The Hover Nozzle is located inside blue nozzle boxes. Collecting a Blue Coin disables the Hover Nozzle temporarily. When Mario jumps off Yoshi, FLUDD will automatically have a full tank of water and be equipped with the Hover Nozzle, regardless of the conditions before Mario jumps on it.
 * Rocket Nozzle - This nozzle allows Mario to blast upwards on a stream of pressurized water after charging up for a brief period of time. He falls without hovering, though he does not take any falling damage. However, it cannot be used when Mario is in the water, so Mario has to jump from the water to perform the Rocket Nozzle in a water area. The Rocket Nozzle can be found inside red nozzle boxes and is unlocked after the player gets 30 Shine Sprites.
 * Turbo Nozzle - This nozzle allows Mario to move quickly across land or water. Turning is more difficult when using this nozzle on land than using it on water. It rapidly uses up a large amount of water when used on land. It also allows Mario to break through orange and green doors, which are otherwise immovable. The Turbo Nozzle can be found inside gray nozzle boxes and is unlocked after the player gets 25 Shine Sprites.
 * Racket Nozzle - This nozzle only appears in Super Mario-Kun. In it, Mario tells FLUDD that it should switch to the Rocket Nozzle. In the next panel, FLUDD's nozzle turns into a tennis racket, hitting a ball, and Mario complements FLUDD for the return. Mario then yells at FLUDD for using the Racket Nozzle instead of the Rocket Nozzle.

Trivia

 * When FLUDD scans Mario in Super Mario Sunshine, a little window in the bottom left corner shows short gameplay clips of boss battles in various Mario games, namely Super Mario Bros., Super Mario World, and Super Mario 64. After Bowser is beaten at the end of the game and FLUDD is looking at Mario, the window shows the Game Over screen from Mario Bros. In addition, in the bottom right corner, the titles of several other Mario games that Mario had been in up to and including that point are shown, though they are backwards with no spaces between the words, so they normally cannot be read by the player. The game titles as they are displayed when FLUDD scans Mario are as follows: MARIOBROS, SUPERMARIOBROS, SUPERMARIOBROS2, SUPERMARIOBROS3, SUPERMARIOWORLD, SUPERMARIOKIRT, SUPERMARIO64, MARIOKIRT64, and MARIOSUNSHINE ("KART" is misspelled "KIRT" in the game titles for Super Mario Kart and Mario Kart 64, which is likely due to a mistranslation of the kā syllable in their Japanese titles). In the center left corner, the profile of Mario is shown in Japanese hiragana. The profile is as follows: きのこおうこくのまりお (Mario of the Mushroom Kingdom), しゅくてき くっぱ (Nemesis: Bowser), しょくぎょう はいかんこう (Occupation: Plumber), すきなたべもの すぱげってぃ(Favorite food: Spaghetti), すきなひと ひみつ(The person I love: Secret), きらいなもの どくきのこ(Dislikes: Poison Mushroom), たいじゅう ひみつ (Body weight: Secret), しんちょう ふめい (Height: Unknown), せんしょくたいのかず ふめい (Chromosome number: Unknown), おとうさんのなまえ しらない (Father's name: Do not know), おかあさんのなまえ しらない (Mother's name: Do not know).