Shadow Ball (シャドーボール, Shadow Ball) is Mewtwo's neutral special move. The move itself consists of Mewtwo concentrating shadow energy into a round ball to toss at opponents. It works as an auto-charge special.
When the B button is pressed, the Shadow Ball will begin charging. It can be fired at any time by pressing B again while charging. It will deal gradually more damage and knockback the bigger it gets. The player can cancel the move and save the charge by shielding, rolling, spot dodging, or, to cancel with no additional action, by lightly tapping the shield button. Mewtwo can also charge the move in the air, where canceling it will make Mewtwo stop its charging animation normally as opposed to shielding or rolling.
When a full charge is saved, both of Mewtwo's hands will constantly glow with dark power. In Melee, only Mewtwo's left hand glows.
Unlike most auto-charge moves, even when Shadow Ball is fully charged, Mewtwo will continue to hold it until the player releases it or cancels. In Melee, a charging Shadow Ball does electric damage and traps an opponent upon contact; from SSB4 onward, it no longer has a hitbox while charging. Once fired, the ball will travel in a wave-like path, which can make it hard to aim but equally difficult to avoid. A fully charged Shadow Ball does heavy damage and knockback, and if shielded, it will damage a shield by about half health. It explodes on contact with a surface, though the explosion is aesthetic only and lacks a hitbox.
The move has a considerable amount of recoil when used in mid-air, and as of Ultimate, it will push Mewtwo back about a quarter of the length of Final Destination, so one must be careful not to use it too close to the edge. However, this can help with recovery if Mewtwo is facing in the opposite direction of the edge.
Mewtwo's forward throw also involves Shadow Balls. Mewtwo will telekinetically throw its opponent forward, then hit them with five small Shadow Balls. Unlike the standard version, these travel very fast and in a straight line. They can hit other opponents in addition to the one thrown and can be SDI'd, reflected, or absorbed.
There are two ways of B-reversing with Shadow Ball, depending on if it is full-charged or not.
The shadow glitch is a glitch exclusive to version 1.0 of Super Smash Bros. Melee. It was discovered by INF8, Veg, and Simna ibn Sind; it allows the Shadow Balls in Mewtwo's forward throw to be caught as items. This requires three characters: one Mewtwo, one character to catch the shadow ball, and one other character to be thrown.
The player must have Mewtwo grab and forward throw another player (this works well with Bowser). Then, they need to make the third character jump and air dodge into the resulting stream of Shadow Balls and press the Z button to catch one. This will not make the normal item-catching sound effect, so the player must look at the character's hands afterward to determine if the attempt was successful.
If the Shadow Ball is thrown, it will freeze the game unless it is quickly recaught.
Special Move customization was added in Super Smash Bros. 4. These are the known variations:
Like the other DLC characters, Mewtwo lacks custom move variations (aside from the glitch ones in 1.0.6).
Shadow Ball is a Ghost-type attack in the Pokémon games. While it was introduced as an attack in the Generation II games, its first appearance in any form of Pokémon media was in the movie Mewtwo Strikes Back, where it was used by Mewtwo. It was available as TM30 from its introduction up to Ultra Sun & Ultra Moon, after which it became TM43 in Let's Go Pikachu & Let's Go Eevee and TR33 in Sword & Shield. It can be taught to a large variety of Pokémon, including Mewtwo and several other Psychic-types.