Randomness

Randomness is the concept of unpredictable events. It is a critical factor in many video games, including the  series. Random events challenge players to think quickly and cause a game to never be played the same way twice.

Mechanics of computer-generated random numbers
Computers are unable to generate truly random numbers. They can only create a series of pseudo-random numbers. If a computer were to start out with a certain seed (initial number), one could predict the entire sequence of pseudorandom numbers to follow. It is believed this is how Replays are saved; the system only saves the seed instead of all random events.

General

 * Computer players do things randomly: the higher the computer's level, the more likely it is to do a specified action.
 * Random items appear in predetermined places at random times, with preset ratios.
 * When strong enough knockback to cause tumbling is inflicted on a character with at least 100% damage after getting hit, there is a 30% chance they will be sent reeling instead. The difference alters the character's hurt box and in Smash 4, where reeling decreases hitstun by one frame and prevents characters from teching on the ground while in hitstun.
 * Tripping is a random event that may occur in two ways:
 * In Brawl only, whenever characters initiate a dash or turn around from a run, with chances of 1% and 1.25% respectively.
 * From Brawl onward, by any attack with knockback that keeps targets on the ground. These have both a base trip chance of 13.5% (7% starting in version 1.1.4 of Smash 4), which requires knockback to be higher than 55 units, and a bonus trip chance exclusive to specific attacks, which is added to the base chance to determine the final trip chance (for example, a move with a bonus trip chance of 30% will have an effective trip chance of 43.5% or 37% respectively).
 * KOs that occur on the upper blast line are randomly chosen from being a Star KO, a Screen KO, or from Smash 4 onward, a Blast KO. Also in Smash 4 onward, this randomness is removed if the victim takes high enough knockback, instead forcing a Blast KO.
 * In the Name Entry, a name can be picked randomly from a predefined list.
 * It is random when characters will do one of their idle poses and which one they will do.
 * It is random where characters will appear when starting a match.

Random character/stage select
The following are random occurrences during character and stage selection.


 * In SSB, there was no feature to allow players to select a random character directly. However, computer players were selected randomly once entered. Random stage select would choose one of the eight or nine available stages.
 * In Melee, once all characters are unlocked, placing one's selection token on either of the two blank corners of the selection grid would move the token onto a random character. CP players would be randomized. Random stage select would select from any of the unlocked stages. Once all stages are unlocked, the player can choose which stages to exclude from the selection list.
 * In Brawl, Smash 4 and Ultimate, the character selection screen has a designated space for choosing a random character. A "?" appears on the player's selection bracket and no one will know who that player will be until the match begins. (The system will choose and begin loading the character as soon as Random is selected, however.) This random function also selects a random costume for the character, and is how CPUs are entered by default. Randomly choosing a stage behaves the same as Melee, but the player cannot choose to leave out individual custom stages. In addition, custom stages saved on the SD card cannot be randomly chosen.
 * When the player selects the Mushroomy Kingdom stage in Brawl, it will randomly choose between the above ground level and the underground level, though which stage it chooses can be controlled through holding a specific button. The same applies to which Pokémon will appear when Spear Pillar is chosen, and which Metal Gear will appear when Shadow Moses Island is selected.
 * In Brawl, when is selected without selecting any of his Pokémon, he will start off with a random one. This was changed in Ultimate, where it starts with Squirtle by default and the player can change which Pokémon starts the match.
 * Mii Fighters are never chosen through random. They are the only characters with this property.
 * In Smash 4, when playing a local battle with CPUs, if the player is fighting CPUs with randomly selected characters while the player is using the same character for every match, the random character selection will never choose the player's character. This only seems to work for 1 player.

Random events intrinsic to a fighter
The following are random occurrences that apply to individual fighters.


 * In Ultimate, 's Super Jump Punch will sometimes cause Mario's hat to change into Cappy, and the coins spawned to be regional ones from New Donk City. The effect is purely aesthetic.
 * The barrels launched from 's up special, Rocketbarrel Boost, have a random trajectory if broken.
 * 's smash attacks have a 1/8 chance of dealing a critical hit, causing them to deal 2x damage and knockback.
 * His Command Selection generates four random spells from a pool of 21 unique special moves, each with their own probability of appearing. Some spells cannot appear alongside others (eg. Sizz and Sizzle).
 * Two of the Command Selection moves, Whack and Thwack, have a random chance of instantly KOing opponents, which increases as both the user's and foe's percentage go up.
 * Hocus Pocus is a spell that specifically causes a random effect to occur.
 * It is also random where Hero will land on stage when using Zoom.
 * 's side special, Razor Leaf, curves in a random direction (up, down, or no curve).
 * 's side special move in Brawl, Waddle Dee Toss, can produce a Waddle Dee (71.4%), a Waddle Doo (20.4%), or a Gordo (8.2%). There's also a small chance that a Capsule, containing a random item, is produced. A Capsule will not appear, however, if it is turned off on the Item switch, and only items turned on will appear from the Capsule.
 * 's Gordos from his side special in Smash 4 can either stick to a wall they come in contact with, or rebound off it, with a 50% chance of each. If the wall doesn't allow wall jumping, however, they will always rebound off it.
 * King Dedede's Final Smash, Waddle Dee Army, produces random minions in the same proportions as the Waddle Dee Toss.
 * Kirby has a chance of losing his Copy Ability when hit by an attack. He can transform into 6 different objects when he uses Stone, though this only affects the move aesthetically, and has no effect on gameplay.
 * Luigi's side special, Green Missile, has a chance of misfiring in Melee and Brawl, and  in SSB4 and Ultimate. Additionally, starting in Brawl, Green Missile has a 50% chance of getting Luigi stuck in a wall if he makes contact with one above a certain speed.
 * Luigi's Final Smash in Brawl, Negative Zone, can cause a variety of random, harmful effects.
 * Mr. Game & Watch's side special, Judge, has 9 randomly-chosen attacks, each with different strengths and effects. The chance of pulling each number is equal, and Judge will not pull the last two numbers pulled. When the move has not been used in a match, 1 and 2 are considered to be the previous two moves pulled. In Smash 4, Mr. Game & Watch can get any number regardless of the last two he got, giving every number an equal chance of appearing.
 * The sausages from Mr. Game & Watch's neutral special, Chef, travel in the air randomly.
 * 's neutral special, Pikmin Pluck, produces a random Pikmin species. It is influenced by what type of ground Olimar's standing on. This is no longer the case in SSB4 and Ultimate where Pikmin are pulled in a set order.
 * After making a full loop, 's Boss Galaxian will randomly fly either straight or in a 30° or 45° angle.
 * 's up taunt will randomly choose between 19 different Namco characters or items to show. Three of these are unique to the Wii U version, while two are unique to the 3DS version. All of them return in Ultimate, with some new ones.
 * 's forward smash can hit with 3 different weapons: a frying pan, a golf club, or a tennis racket. Each weapon has an equal chance of being pulled, and the same weapon will not be pulled twice in a row. This was changed in Smash 4: Peach's forward smash cycles between a tennis racket, golf club, and frying pan, in that order. In Ultimate, Peach and her new Echo Fighter can manually select which weapon to use by angling the forward smash; the golf club is used if the move is unangled, while the frying pan and tennis racket are used for upward and downward-angled forward smashes.
 * Peach's down special's Vegetables can have a variety of random faces, with the faces signifying the power of the turnip. The most powerful turnip, which has stitches on its face, has a chance of being pulled. There is also a very small chance of a Beam Sword, Bob-omb, or a Mr. Saturn being pulled instead of a vegetable. And unlike with Capsules being thrown by Waddle Dee Toss, the chance of pulling these items is not affected by whether they are turned on or not. In SSB4, Beam Swords can no longer be obtained from this move, but the chances of getting Bob-ombs, Mr. Saturn, or the stitch-faced vegetable are slightly higher. Daisy retains the same data for her down special in Ultimate.
 * When Peach (or Daisy in Ultimate) uses Toad, the direction of the spores is slightly randomized.
 * The portraits that appear during Peach's Peach Blossom Final Smash (and Daisy's version of the former move, Daisy Blossom) are randomized. This is purely aesthetic.
 * Greninja's down special, Substitute spawns either a log or a substitute doll when executed.
 * The trajectory of the projectile launched from 's up smash can deviate slightly to the right or the left. This is not the case in Ultimate, where it is always launched up and in front of Snake.
 * Snake has a chance of planting a C3 instead of a C4 when his down special is used. This only affects the move aesthetically and does not affect gameplay.
 * There is a rather large chance that will fall from his bike when turning it in Brawl.
 * Villager has a random chance of attacking with either one (30%), two (30%), or three (40%) turnips with his up and down aerials. In Smash 4, his down aerial could only spike if he attacked with three turnips, but this was changed in Ultimate. Although Isabelle in Ultimate has similar up and down aerials, she always uses two turnips instead of one.
 * Villager's Timber will sometimes generate a wood chip when the tree is felled, and it is also random how far the wood chip will fly, and rarely will even produce a fruit which can be eaten to heal damage. It is also random where the balloons from Balloon Trip will fly after the move is finished. Only the lattermost of these applies to Isabelle, due to her functionally similar up special.
 * Dr. Mario's Megavitamins' colors are randomized, although the effect is purely aesthetic.
 * Duck Hunt will cycle through a group of five gunmen for their Wild Gunman move in random order with each use of the move until each gunman is summoned once, then reset the process after the fifth gunman.
 * Rosalina & Luma's Star Bits fly in a slightly randomized trajectory each time the move is executed. The color of the Luma after the first time it respawns is also random, being either yellow, red, blue, green, cream, or Polari.
 * Joker's All-Out Attack Final Smash will randomly choose between summoning Ann Takamaki, Ryuji Sakamoto and Morgana, or Makoto Niijima, Yusuke Kitagawa and Haru Okumura to assist with either Futaba Sakura or Morgana narrating.
 * The eggs fired during Banjo & Kazooie's Egg Firing and Rear Egg bounce in a somewhat unpredictable fashion, especially the latter.
 * Sheik's needles fire at random heights.
 * When King K. Rool does not catch his crown after using Crownerang and it falls offscreen, it will reappear either in front or behind him.
 * Sephiroth's Final Smash, Supernova, has a random effect on each opponent it hits, in addition to the damage it deals.

Random events intrinsic to a stage
The following are random occurrences that occur in specific stages.

In Super Smash Bros.

 * In Hyrule Castle, the tornado hazard appears at random.
 * When entering a pipe in, the destination pipe is chosen at random.
 * On Saffron City, the Pokémon that appears from the door to the Silph Co. building is chosen at random.

In Super Smash Bros. Melee

 * The layout of the track in Big Blue is randomly generated.
 * The rate at which the acid in Brinstar rises and falls is randomly chosen from preexisting patterns.
 * The stage in Brinstar Depths turns in a random direction when hit by Kraid.
 * Arwings and Wolfens appear at random on Corneria, as well as have randomly chosen flight paths, and attack at random.
 * The stage hazards on Flat Zone appear at random.
 * The two lower platforms on Fountain of Dreams slowly move up and down in a random pattern.
 * On Green Greens, whether a falling block is a normal block or bomb block is chosen randomly.
 * Which direction the stage moves in on Icicle Mountain, as well as the speed it moves, is random.
 * On Mushroom Kingdom, ? Blocks instead of normal blocks spawn randomly.
 * When and which cars drive by on Onett is random, though a sound and visual warning is given before they drive by.
 * On Pokémon Stadium, which stage transformation occurs is chosen at random. However, it'll cycle through all four transformations before repeating, and a long warning is given before the stage transforms.
 * Switches and Banzai Bill will appear on Princess Peach's Castle at random.
 * Like on Corneria, Arwings and Wolfens appear at random on Venom.
 * On Yoshi's Story, Shy Guys appear at random in packs up to six, which carry food if items and food are turned on. These Shy Guys can be attacked, and will drop their food if carrying it.
 * When the Star Fox Smash Taunt is performed, a random dialogue plays.

In Super Smash Bros. Brawl
All returning Melee stages retain their random elements from Melee.


 * Donkey Kong wakes up at random on 75m, and the amount of time he is out is random.
 * King Bulblin appears at random on Bridge of Eldin, and will drop a bomb on the center of the stage at random (though he'll always drop a bomb during his first appearance). Bulblins straggling behind King Bulblin, which can be attacked, will also appear at random.
 * The order of the locales in which Delfino Plaza stops at is random. When the stage rises up to move from a stopped at location, its platform arrangement is chosen randomly from preexisting patterns.
 * Platforms appear at random during the beginning portion of Flat Zone 2, as well as the treasure diver to collect items. Which game the stage transforms to is also chosen at random.
 * How often the stage flips on Frigate Orpheon is chosen randomly from preexisting patterns.
 * Where the checkpoint lampposts appear on Green Hill Zone is random. Different portions of the stage will also crumble away at random if players do not destroy these stage portions themselves.
 * On Halberd, the Combo Cannon on the bridge portion of the stage will attack players at random, with a randomly chosen weapon. When the stage rises up from the bridge, whether or not the camera is properly zoomed in until the next bridge stop, also occurs randomly.
 * The stage on Lylat Cruise slowly tilts at random and the background appears randomly.
 * When and which stage hazards on Mario Bros. occur is random.
 * When and where the Ultimate Chimera spawns on New Pork City occurs randomly.
 * Stage hazards on Norfair occur at random. Similar to Brinstar, the pattern of the lava's rising and dropping is chosen randomly from preexisting patterns.
 * Which transformation on Pictochat occurs is random, though, like Pokémon Stadium, it'll cycle through all possible transformations before repeating.
 * Stage events on Pirate Ship occur at random.
 * Like with Pokémon Stadium, which stage transformation occurs on Pokémon Stadium 2 is chosen at random, with the stage cycling through the four transformations before repeating, and gives players a long warning before transforming.
 * Which location is stopped at on Port Town Aero Dive is chosen randomly. Cars will also drive by some of these stops at random.
 * When and which Metal Gear appears in the background on Shadow Moses Island is chosen randomly. However, this has no impact on gameplay.
 * The starting position of the floating platform on Smashville is random, as well as the occurrence of the balloon.
 * The background Pokémon in Spear Pillar attacks at random, with randomly chosen attacks.
 * Food from  spawns randomly on Summit.
 * On WarioWare, Inc., the stage transforms into a randomly chosen microgame. When a player wins one of these microgames, they are randomly rewarded with the effects of a Starman, Super Mushroom, Food, or nothing.
 * On, the support ghost appears in predetermined places at random. Like Yoshi's Story in Melee, Shy Guys carrying food (if items and food are turned on) will appear randomly in packs up to four, which can be attacked to cause them to drop their food. Which season the stage starts on is also chosen randomly, though this has no effect on gameplay.

In Super Smash Bros. 4
All returning stages from previous games (including DLC stages) retain their random elements.


 * The ducks in Duck Hunt appear in different starting positions and travel along differing paths. Grass patches also appear somewhat randomly in Duck Hunt.
 * The behavior of Metal Face in Gaur Plain is random.
 * The stage hazards in Midgar are selected at random each time one is summoned.
 * The layout of the stage in Super Mario Maker is randomly arranged. The theme also randomly switches between Super Mario Bros., Super Mario Bros. 3, Super Mario World and New Super Mario Bros. U.
 * In Umbra Clock Tower platforms and debris can appear in a randomly selected pre-determined arrangement.
 * The behavior of the Yellow Devil in Wily Castle is somewhat random. The platforms also travel random paths.
 * ? blocks in 3D Land spawn in random items.
 * 5 different variations of Arena Ferox can appear at random.
 * The Balloon Fight stage has 3 layouts, selected at random. Sparks will also randomly be fired out of clouds.
 * In Find Mii the Dark Emperor will randomly upgrade or downgrade the fighters wearing certain color clothing, fly into the foreground, damaging fighters who he touches and make one of the platforms sink. The cage contains either a prince or princess Mii.
 * In Living Room blocks and other objects will randomly fall onto the stage. The puppy in the background is randomly selected.
 * In Magicant Dungeon Man and Flying Men will occasionally appear. Various stage elements can also appear. A rip will occasionally appear in the background, showing points in Ness and Ninten's adventures.
 * Pac-Dots and Bonus Fruits appear on the Pac-Maze stage. Where the Power Pellets appear each time 100 points is collected is also random.
 * Drawings will randomly appear on the PictoChat 2 stage.
 * In Rainbow Road the platform will land in several areas, but not necessarily in every area.
 * Birds will occasionally carry platforms onscreen in Spirit Train.
 * The interior of each of the six rooms in Tomodachi Life is random.
 * The layout of the Tortimer Island stage is random.
 * N's Castle in Unova Pokémon League will occasionally rise, summoning ramps to crash into the sides of the stage. In this state, Reshiram and Zekrom can attack with flames and electricity. In the Battlefield/Omega versions of the stage, Whimsicott, Shaymin, and Milotic can appear in the background. However, this has no effect on gameplay.
 * Platforms can appear and disappear at random in Coliseum.
 * The games in Flat Zone X are selected in a random order.
 * The layout of Gamer is randomly selected from several arrangements. 5-Volt will also randomly appear and look at various sections of the stage, dealing high damage to anyone she sees.
 * A Peckish Aristocrab will occasionally run across the stage in Garden of Hope. The Pikmin will also occasionally appear to repair the bridge, stick, and pot. The stage elements are also arranged somewhat randomly.
 * The foreground or background of Jungle Hijinxs will occasionally sink. Cannons appear randomly.
 * The stage in Kalos Pokémon League will randomly transition between the Dragonmark, Blazing, Ironworks and Flood chambers, which themselves have 2 different variations.
 * The stage will stop in various locations in Mario Circuit.
 * The posts in Miiverse appear somewhat randomly.
 * The exact pattern of transitions in Mushroom Kingdom U is random.
 * Ridley's behavior in Pyrosphere is partially random.
 * The stage in Skyloft will stop in various locations.
 * The platforms in Wii Fit Studio appear in random positions.
 * The platform in Wuhu Island stops in various locations.
 * In PAC-LAND, it's random if the healing balloons or the "Super-Pac" item appears.

In Super Smash Bros. Ultimate
All returning stages from previous games (including DLC stages) retain their random elements. Most of these elements can be turned on or off via the Hazards toggle.


 * The musicians of the New Donk City band and Pauline will randomly float by in the background in New Donk City Hall. Touching them will have their respective instrument be added to the music if the music is set to "Jump Up, Super Star!" or "Ground Theme (Band Performance) - Super Mario Bros."
 * Dracula's Castle has candles that will drop a random item when destroyed, assuming items are on.
 * Trains will randomly drive past on Mementos, the one below the train able to damage fighters. A third platform decorated with a cracked screen will occasionally appear on the right. Finally, a large triangle-shaped wall will appear on either side or the top of the stage for a limited amount of time.
 * A random layout of platforms on Yggdrasil's Altar will occasionally appear. Additionally, chests may appear on platforms, containing a random item. However, the chests have a chance of being a Mimic instead.
 * Spiral Mountain features wooden platforms and floating patches of ground that occasionally appear in a random layout.
 * Minecraft World features one of six randomly chosen biomes, each with a different layout. Like Mushroomy Kingdom in Brawl and Boxing Ring, each biome can be selected manually with button inputs on the stage select screen.

Random events intrinsic to an item
The following is random behavior of specific items.

In all Super Smash Bros. games

 * Which items appear from container items is chosen randomly from what items turned on. There is also a random chance of containers not containing any items and instead being explosive (with the exception of Sandbag).
 * Characters have a random chance of dropping an item when hit, which depends on the damage the attack deals. In SSB and Melee, this chance is determined by the formula damage/60 for all items, meaning an attack that deals at least 60% damage will guarantee that the item is dropped. In Brawl and Smash 4, the formula is CEIL(damage)/70, but certain items use their own formula:
 * In Brawl, the Dragoon parts and Smash Ball use INT(damage)/50.
 * In Smash 4, the Dragoon and Daybreak parts use INT(damage)/100.
 * What Pokémon a Poké Ball spawns is random, with each Pokémon having a different chance of appearing. If the Pokémon targets a specific player, which opponent is targeted is also chosen at random. Certain rare Pokémon (namely Mew, Celebi and Jirachi) have fixed chances of appearing, depending on the games: in Smash 64 (in which only Mew appears),  in Melee (which includes Celebi) and  in Brawl (which includes Jirachi).

In Super Smash Bros. Melee

 * When food spawns, the specific food that appears is random.
 * The Hammer head on a has a  chance of dropping off when the Hammer is picked up.

In Super Smash Bros. Brawl
All returning items from Melee retain any random elements they had in Melee.


 * Like with Poké Balls, which character an Assist Trophy spawns is chosen randomly. Which opponent the Assist Trophy character targets (if any) is also random.
 * Occasionally, Electrode will fail to explode. However, after a short time, Electrode will explode anyway, and will explode when thrown.
 * Similarly to Electrode, Smart Bombs occasionally fail to explode when thrown or hit. They will eventually explode if left uninterrupted, or will explode if they come in contact with a hitbox that deals fire damage.
 * Golden Hammers have a chance of spawning as a Golden Squeaky Hammer, which while indistinguishable from appearance, produces hitboxes that are completely harmless, and produces a "squeaky" noise when it hits someone.
 * Instead of turning all opponents small, Lightning may randomly turn the player who grabbed it small, or turn all opponents giant.
 * Instead of slowing all opponents down, a Timer may randomly slow down the player who grabbed it, or slow down all players.

In Super Smash Bros. 4
All returning items from previous games retain any random elements they had.


 * If there are at least 2 opponents, the Boss Galaga item will target a player at random.
 * While its exact pattern is unknown, the spawning position of the multiple Cuccos that attack players seem to have some element of randomness to them, even if they are targeting a specific player.
 * The item generated from plucking is selected at random from a list of potential items.
 * Similarly to the Poké Ball the Pokémon spawned from the Master Ball is selected at random from all the legendary Pokémon in the game (as well as Goldeen).
 * If all possible targets have the exact same damage and score/number of stocks, then the Spiny Shell will pick a target at random.

In Super Smash Bros. Ultimate
All returning items from previous games retain any random elements they had.


 * Green Shell may now rebound off a struck opponent instead of traveling continuously.
 * Beastball will target a random opponent if there is more than one opponent.
 * Abra will get close to an opponent, teleporting with them to a random spot, often times off stage.

Randomness in competitive play
Some randomness that can't be controlled and/or has little impact on gameplay is considered acceptable (if undesirable) in competitive play. For instance, Star and Screen KOs occur randomly and cannot be disabled, so the mechanic is always active. However, excessive, uncontrollable randomness is usually considered degenerative to competitive play. The reasoning is that if randomness has too much of an impact on gameplay, the winner of the match could simply win by being luckier with random events, rather than outplaying their opponent. Therefore, to prevent people from winning by being the luckier player and to ensure the more skilled player wins, steps are taken to limit the effect of randomness in competitive play. These steps include turning off all items, using stage striking instead of random selection to choose the stage for the first game in a tournament set, and banning stages whose random events have too large of an impact on gameplay within the stage (such as WarioWare, Inc.).