Metal Mario

Metal Mario is a boss in Smash 64 & Melee, and a form in Melee, Brawl,  & Smash 4.

In Super Smash Bros.
Metal Mario appears on Stage 9 in 1P Mode.

In Super Smash Bros. Melee
Metal Mario appears as a boss, alongside Metal Luigi. He also appears when Mario uses a Metal Box.

In Super Smash Bros. Brawl & Smash 4
Metal Mario appears when Mario gets a Metal Box.