Metal Mario (form)

Metal Mario is a powered up form of Mario that first appeared in the game Super Mario 64. Metal Mario is tougher, stronger, virtually invincible, and can be hurt only by long falls. This form is acquired by picking up the Metal Cap from green ! Blocks or Metal Boxes.

The Metal form would later be granted to other characters through use of different items, though the form itself would act the same.

Super Mario 64
When Mario uses a Metal Cap in Super Mario 64, he becomes Metal Mario, a living embodiment of metal. In this form, Mario is invincible and can destroy enemies just by running into them. Metal Mario is also very heavy, and as such, can withstand strong winds, underwater currents, and can walk on the bottom of bodies of water. In addition, he doesn't need to breathe, meaning he can stay underwater without worrying about air until the metal power runs out. Despite being heavy, Metal Mario still retains all his physical speed as well his athletic jumping abilities, however, he'll sink in quicksand faster.

Metal Mario can combine his Metal Cap with the Vanish Cap to become Vanish Metal Mario, which will enable him to go through certain walls while maintaining his metal form's strengths and weaknesses.

Super Mario 64 DS
In the remake of Super Mario 64 for the Nintendo DS, Super Mario 64 DS, only Wario could turn metallic and become Metal Wario by using a Power Flower. He is able to walk on Lava and Freezing Water, though after a while he begins to sink and if he goes below the surface he will lose a life. Metal Wario's other abilities and vulnerabilities are the same as Metal Mario's.

Dr. Mario 64
At one point, Dr. Mario accidentally eats some Megavitamins and turns into a Metal Mario form. This metallic Dr. Mario also appears as a separate, playable Metal Mario character.

Super Smash Bros. series
A Metal Mario character appeared in the original Super Smash Bros. as a boss. The sequel, Super Smash Bros. Melee also featured this permanently metal plumber as well as a separate Luigi character as bosses.

In Super Smash Bros. Melee and Super Smash Bros. Brawl, players could pick up the Metal Box as an item, and gain metal forms for a limited time, all boasting the same attributes as the non-playable Metal Mario: namely, being heavier and silent, except for clanging metal noises made when they move. This metal form can also be used as a setting in the Special Brawl of Super Smash Bros. Brawl.

In Classic Mode of both Melee and Brawl, a character in metal form will always be one of the selected challengers. In Melee, this metal character will always appear at Level 10, whereas in Brawl, one will appear at random anywhere from Levels 6 to 10.

Mario Party series
The metal form also appears in Mario Party 6 and Mario Party 7 when one of the playable characters uses a Metal Shroom Orb on him- or herself to avoid traps.

Mario Strikers Charged
It appears that Mario can become Metal Mario in Mario Strikers Charged when he performs his Mega Strike.

Trivia

 * In an interview published in 1991 (in Nintendo Power's Mario Mania Player's Guide), Shigeru Miyamoto reportedly said: "Who knows what Mario will look like in the future? Maybe he'll wear metallic clothes!" Metal Mario then appeared in 1996.
 * In the Super Smash Bros. series, anyone who turns into a metal form loses the ability to speak (except Samus Aran, Captain Olimar, R.O.B. and Mr. Game & Watch, the latter two of whom technically don't speak anyway, although they make their beeping and mechanical noises instead).
 * While the Metal Mario form itself is not in the game, Silver Luigi in New Super Mario Bros. 2 looks very similar to Metal Mario, right down to the metallic finish.