Mew

Mew (, Mew) is a creature in the media franchise. It has appeared as a very rare Pokémon in every game of the Super Smash Bros. series.

In-universe, Mew is the origin of Mewtwo, with the latter being its genetically-altered clone.

Origin
Introduced in, Mew is a pink, feline, Psychic-type Pokémon that somewhat resembles an embryo. It is often depicted as floating through the air, sometimes encased in a bubble of energy. Within the, it is registered at #151 as the "New Species Pokémon", being the last Pokémon in the Kanto Pokédex. It is said to be the origin of all other species of Pokémon, and as such, it can legitimately learn any TM move and most tutoring moves in the game. Sightings of Mew are very rare, as the Pokémon is normally invisible, only revealing itself to the pure of heart.

Some time in the past, Mew was encountered and captured by scientists, who performed a multitude of experiments until it gave birth to a clone, dubbed Mewtwo. Oddly enough, Mew is numbered after Mewtwo in the Pokédex, most likely due to its late inclusion during the franchise's development.

According to developer anecdotes, Mew was never originally intended to be encountered at all, only being mentioned as part of the games' backstory. However, just two weeks before the games were due for release, removing the development tools left enough unused space for a single Pokémon; programmer included Mew as a secret encounter, something even Nintendo was unaware of.

Because of its hidden nature, Mew became the first. It cannot be obtained through regular gameplay, and thus the only way to obtain it legitimately is through real-life distribution events. In most of these events, Mew is obtained without fighting it.

The only game where Mew can be encountered and fought normally is Pokémon Emerald, where the player can participate in an event to visit a deserted island where it resides.

Its depiction within the Super Smash Bros. series is similar to Mewtwo, in that both of them are loosely based off of their first movie incarnations; Kōichi Yamadera, its actor from the movie, also provides its voice in Smash.

Mew's appearance in a bubble is based on its appearance in . The move Mew uses in its appearances in Smash is ; since Mew is capable of learning all TM and HM moves, it can learn the move from in all games. Its elusive nature is also reflected appropriately; it is among the rarest Pokémon to encounter in each installment, and doing so is usually acknowledged through a notice.

In Super Smash Bros.
In an official poll held on Smabura-Ken (the game's official Japanese website) regarding characters for a potential sequel, Mew placed 10th with 24 votes.

As a Poké Ball Pokémon
Mew makes its first appearance in Super Smash Bros. It will not do anything, but will instead remain on the screen for a few seconds, then fly off. Once the player has unlocked any of the hidden characters, Mew has a 1-in-151 chance of appearing in the game, in reference to Mew's Pokedex number and the total number of Pokémon at the time when Super Smash Bros. came out. If Mew is summoned by the player in the 1P Game, the player is awarded the "Mew Catch" bonus, worth 15,000 points.

As a Poké Ball Pokémon
Mew returns in Super Smash Bros. Melee, appearing in a bubble and flying off instead of attacking, again causing no harm to any fighter. Mew can only appear from a Poké Ball if all characters are unlocked. This makes Mew one of only two unlockable Pokémon in Melee, the other being Celebi, both having a 1-in-251 chance of appearing related to the total of existing Pokémon at the time. The first time the player sees a Mew, they will receive a notice commemorating the occasion.

Trophy
Mew is featured as a collectible trophy; to attain it, the player has to clear the All-Star Mode on Hard or Very Hard difficulty, though the player is allowed to use continues.

As a Poké Ball Pokémon
It softly ascends to the sky while dropping off one CD. It’s your lucky day if you meet this one. Mew returns yet again in the third installment, and it now drops a CD before flying away. Along with Celebi and Jirachi, it is one of the rarest of all the Pokémon, having a 1-in-493 chance to spawn, in reference to the total number of Pokémon as of Generation IV (the then-current generation of the series). After encountering Mew for the first time, the player receives a notice as in Melee.

If the player has collected all of the CDs, Mew will instead drop stickers, like Jirachi does. If the player has collected all CDs and stickers, Mew drops nothing.

Trophy
Mew also returns as a collectible trophy, obtained randomly through the Coin Launcher, or found in The Subspace Emissary or the rest areas of All-Star and Boss Battles.

As a Poké Ball Pokémon
Mew returns in Super Smash Bros. 4 as either a Poké Ball or Master Ball summon. It drops a random trophy or Custom Part as it flies away, taking over Celebi's role in Brawl. In the Wii U version, it may also drop CDs. This is the first game where Mew does not need to be unlocked.

As a Poké Ball Pokémon
Mew returns as a Poké Ball summon. However, as in-battle collectible spawns have been removed entirely, it has no effect in-game at all, much like its pre-Brawl behavior, now making it completely useless.

Mew cannot be summoned on Corneria or Mushroomy Kingdom.

Spirit
Mew also appears as a Legend-class support spirit.

Mew's Spirit Battle uses a puppet fighter and is fought on the  stage. During the battle, the player must defeat Mewtwo in 1:30, referencing the short amount of time that Mew appears on-screen as a rare Poké Ball Pokémon before flying away in the Super Smash Bros. series. Also, Mewtwo will turn invisible while the stage is covered in fog, referencing Mew's ability to turn itself invisible at will, who normally appears to those who are pure of heart.

Trivia

 * Mew, Goldeen, and Snorlax are the only Pokémon to appear as Poké Ball Pokémon in every game.
 * Mew is also the only Mythical Poké Ball Pokémon to appear in every game.
 * Mew is also the first Mythical Pokémon to appear in Smash.
 * If Mew is sent out during Smash Tour, it will not drop anything.
 * The odds of Mew being released from a Poké Ball in the first 3 games reflect the total number of Pokémon known at the time of that Smash game's release: it has a 1 in 151 chance of appearing in Smash 64, referencing the number of Pokémon introduced in Generation I; a 1 in 251 chance of appearing in Melee, referencing the total number of Pokémon known during Generation II and a 1 in 493 in Brawl, referencing the total number of Pokémon in Generation IV.