Bomb (WarioWare series)
From the Super Mario Wiki
In the WarioWare games since WarioWare: Touched!, it is used as a timer to show how much time is left to complete the current microgame. (Prior to WarioWare: Touched!, the games used a generic bomb instead.) The fuse on the bomb is lit and slowly burns out. When the lit fuse reaches the bomb, the bomb will explode and the microgame is over. The fuse typically takes 4 seconds (8 beats) to burst, but certain microgames that require more examination or articulation have an extended time, up to 8 seconds (16 beats). All of Orbulon's microgames have 8 seconds (16 beats) of time, as they require full thought (except for 12 of them in WarioWare: Smooth Moves and 11 of them in WarioWare: D.I.Y.).
In WarioWare: Touched!, a bomb appears in the character select screen when Wario is present as Wario-Man. If the player feeds the bomb to Wario Man, he turns back into Wario.
In Super Smash Bros. Brawl in the WarioWare, Inc. stage, when a microgame appears, the bomb appears as a timer to show the player how much time is left to complete the current microgame, just as in the WarioWare games. When the lit fuse reaches the bomb, it will explode and the players return to the main area of the stage. The time given to complete the microgame is always 4 seconds (8 beats). It also appears in the back of Wario's biker jacket in this same game, although not seen on his jacket in the WarioWare games.
The bomb appears in Mario Sports Mix as part of Wario's special shot, now colored yellow. After exploding, it creates a large cloud of smoke that covers part of the field.