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; in SSB4, 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, especially when used in mid-air, 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. The recoil causes Mewtwo to slide back about half the length of Flat Zone when it performs this move in midair but lands before the animation is complete. In later patches of Smash 4, however, Mewtwo suffers less recoil than before.
Mewtwo's forward throw also involves Shadow Balls. Mewtwo will telekinetically throw its opponent forward, then hit them with multiple small Shadow Balls. This throw will at minimum deal 9% damage, but in certain situations, the move can deal up to 18% damage. These Shadow Balls 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 is available as TM30 in all games since its introduction, and it can be taught to a large variety of Pokémon, including Mewtwo and several other Psychic-types.