Duon

Duon is a boss in the Subspace Emissary of Super Smash Bros. Brawl, where it is located atop the Battleship Halberd Bridge. In the game, it is fought by Fox, Falco, Snake, Lucario, Zelda/Sheik, and Peach. After Snake had thrown Mr. Game & Watches out of the Halberd's control room, outside onto the bridge where Sheik/Zelda, Peach, and Fox stand. The Mr. Game and Watches land, but are then revealed to be Shadow Bugs. They then turn into Duon, which Fox, Sheik, and Peach get ready to battle. Lucario and Snake jump from the control room's window and land behind the three. An Arwing flies overhead of the five and Duon, and Falco ejects from it. All battle and win; and as this happens, Meta Knight regains control of the Halberd, while the Duon is dertroyed, and after being destroyed, Mr. Game and Watch's trophy appears. It later appears in The Great Maze, where it appears at the same area, atop the Halberd's bridge.

Its' attacks involve spinning rapidly, firing a barrage of missiles, crushing the player by jumping, and shooting lasers in a circular pattern, amongst other attacks.

Trivia

 * The name is most likely based on the word "duo" - meaning "two." This is because Duon has two different bodies attached to each other.