Yoo Who Cannon is a Special Attack that appears in the game Mario & Luigi: Bowser's Inside Story. Originally, it can be found in Toad Town. It returns in Mario & Luigi: Brothership. In both games, it is of the type Bros. Attack.
Appearance[]
As its name implies, the Yoo Who Cannon involves a group of barrels used as cannons. The barrels are wooden, and their design features red and green arrows pointing toward their opening, which has a white lip, and their fuses are visible only when rising. In Brothership, there is a ninth, larger barrel behind the enemy's ranks.
Procedure[]
When using this attack, Mario and Luigi will briefly appear in eight barrels on screen; the player has to remember their positions. After a barrel rises, the player has to press 
for Mario or 
for Luigi, depending on which brother was in the cannon, the player has to press the correct button to damage the enemy before the fuse reaches the barrel. If the wrong button is pressed or if the player takes too long, the other barrels will be destroyed, and it will do less damage and stop the attack. It costs seven SP to use this attack. After teaching Mario how to use Blue Shells, the Blue Paratroopas will give Mario and Luigi the 10 Attack Pieces required to use this move. It, Green Shell and Snack Basket are the only Attack Pieces that are required for the game. In the 3DS remake, the cannons take aim at their target upon priming, rather than facing forward. In both versions, the targeting is random.
This move is available for use in the Challenge Node. It becomes trickier when remembering the order becomes shorter.
In Brothership, there is a ninth cannon placed behind the enemies, which the duplicated Bros. jump into. If the player pushes the X button when all eight enter the cannon, they merge into a wheel and tear through the enemies as they are launched out. The targeting remains random for the first phase, with the final hit now hitting all enemies at once.
Behind the Scenes[]
Etymology[]
The attack's name comes from a pun on the two words, interjection "Yoohoo!", and exclamation for waving and the word "Who?" questioning who is in the barrel.
