The Metal Bros. appear in Super Smash Bros. Melee's Adventure Mode as stage bosses of Battlefield.
Metal Mario[]
Metal Mario more or less reprises his role as a special opponent from the single player game from the first Super Smash Bros. He is fought after defeating the fifteen Fighting Wire Frames. Metal Mario is not a unique opponent; he is actually a Mario that is permanently under the effect of the Metal Box item. He is aggressive, and his recovery is longer, but he falls much faster. If the player has unlocked Luigi, Metal Mario teams up with Metal Luigi for that same battle, making it more difficult.
Metal Mario also appears as a trophy which can be acquired randomly through the 1-P mode or the Trophy Lottery.
Metal Luigi[]
Metal Luigi appears in Super Smash Bros. Melee with Metal Mario after defeating the fifteen Fighting Wire Frames in Adventure Mode. He only appears if the player has already unlocked Luigi. Stat-wise, he is like Metal Mario, very heavy and fast falling, but because he is Luigi, he has different moves than Mario. He also appears with other Metal characters in Classic Mode. He can easily KO himself using Green Missile as he is much heavier.