The Metal Box (緑ブロック, Green Block) is an item from the Mario series that appears in Super Smash Bros. Melee, Super Smash Bros. Brawl, Super Smash Bros. 4, and Super Smash Bros. Ultimate. When broken with a physical attack, the Metal Box encases a character's body in metal for a short period of time, which affects the character in various ways. Images of each character's metal form can be found here.
The Metal Box originates from Super Mario 64 as a green ! Block that materializes after Mario activates its corresponding green Cap Switch at the Cavern of the Metal Cap. Upon being destroyed, it releases a Metal Cap that, after grabbing it, encases him in metal. He becomes more powerful, immune to all damage, and can walk underwater, but at the same time, becomes much heavier, sluggish, and unable to swim. These effects are similar the Metal Box's effects in the Super Smash Bros. series, except that Mario's voice is not suppressed, unless he is submerged underwater.
All green, red, and blue ! Blocks are replaced by red ? Blocks in the Nintendo DS remake of the game, Super Mario 64 DS. After activating them with the red ? Switch at the Rainbow Tower, they can be broken to release the Power Flower, which has different effects on each of the game's four playable characters. This power-up exhibits the same effects as the Metal Cap when picked up by Wario.
The Metal Box encases the character's body in metal when broken with a physical attack. When broken by Rosalina in Smash 4 and Ultimate, her Luma is also metalized. However, when broken by Olimar, his Pikmin are not affected. In addition, only one Ice Climber can hit the box first, so only one can be metalized per box. Finally, Giga Bowser, Wario-Man, Mega Lucario, and Giga Mac are not affected by breaking Metal Boxes.
In all five games, breaking the Metal Box has the following effects:
Metal characters fought in Classic Mode remain metal for the entirety of the battle. In Melee, their stock icon has a distinctly darker, metallic look.
The Metal Box makes its Super Smash Bros. debut in Melee. If it is hit by a projectile, it will disappear. Disjointed attacks like Pikachu's forward smash or any attack from a sword-wielding character will still grant the attacker the metal status. Interestingly, Ness' dash attack is the only disjointed attack that doesn't turn him metal.
Metal characters make different metallic sounds while walking, running, and landing, depending on their weight for the most part. All lightweights except Zelda, Mr. Game & Watch, Mewtwo and the Ice Climbers make a faint "tinging" sound, all middleweights make a standard "clanking" sound, and all heavyweights except Samus, Yoshi, Ganondorf, and Link make a much more noticeable "crunching" sound. Most of the aforementioned exceptional characters make the standard middleweight sound in spite of their weight. Mewtwo doesn't make any sounds, even when landing, and Mr. Game & Watch's footsteps and landing sounds are always beeps.
The Metal Box appears again in Brawl with the nearly same properties it had in Melee, although it will not break when hit by projectiles. It also has an effect on the new ability to swim; while characters will not sink as Metal Mario did in Super Mario 64, they will submerge deeper after falling into the water. This technique is used to reach a secret area in the Glacial Peak level of the Subspace Emissary mode. In Classic Mode, the player might also fight a random metal character. The walking sound effect no longer changes depending on the characters' weights, so everyone has the same sound when walking.
A "Metal" option exists in Special Brawl, which gives every player a permanent Metal Box effect. Lastly, the Metal Box appears again as a collectible trophy.
The Metal Box returns as an item. Its properties mostly remain the same as in previous Super Smash Bros. games. However, its duration can no longer be extended by picking up additional Metal Boxes. In the 3DS version, the metal coating is translucent rather than opaque, but in the Wii U version, the metal texture is both opaque and reflective, with the current stage being reflected on the character's body.
In Classic Mode, the player must also fight a random metal character. The Metal Box is also available as a red item in Smash Tour, giving players the ability to start a battle in metal form. The "Metal" option reappears in Special Smash in Super Smash Bros. for Wii U. Lastly, the Metal Box appears again as a collectible trophy.
The Metal Box reappears once again in Ultimate as an item. The effects are identical to Smash 4, though the metal effect appears to slowly take over the character rather than immediately applying as it did in previous titles, similar to Inkling's ink.
While the Metal Box itself does not have a Spirit, the ability it grants appears as an ability for the Primary Spirit Octobot King.
Equipping the Slippy Toad or Fiora Support Spirits will cause the player to start a match under the effect of a Metal Box.