Bowser Jr. Breakdown

Bowser Jr. Breakdown is a boss minigame featured in Mario Party 9. This and Bowser's Block Battle are the only boss minigames played on Bowser Station, and players cannot choose from three other boss minigames. The same happens on DK's Jungle Ruins.

Introduction
Bowser Jr. flies down in his Junior Clown Car to the stage. A larger version of the car, with two clawed arms sticking out of it, then floats down, and Bowser Jr.'s car links up with the bigger one.

Gameplay
The starting player depends on the game mode being played. If battling Bowser Jr. on the Bowser Station board, the captain takes the first turn. In other modes, an onscreen arrow randomly decides who goes first. The chosen player strikes a victory pose.

Players try to defeat Bowser Jr. by rolling dice numbered one through six to fill the gauge at the top of the screen. Players can shake the Wii Remote to make the dice spin faster. Each number rolled fills that many spaces on the gauge. If the player does nothing for 10 seconds, their character always rolls a 4. If a player's roll fills the gauge to a multiple of three (or to 15 or above, as the gauge stops there), the player attacks and deals that much damage to Bowser Jr. Once a player attacks, the gauge empties. If the gauge is filled to 14—marked by the Bowser Jr. emblem—he rolls a die numbered one through two and smashes the player with a hammer for the number of times indicated by the number rolled, making the player lose that many points. This does not empty the gauge, which means that a player unlucky enough to be attacked by Bowser Jr. also sets up the next player with a guaranteed 15 points.

When Bowser Jr. loses half of his health, the larger car's eyes change color from yellow to red, and Bowser Jr. adds two more Bowser Jr. spaces to the gauge. The new spaces are randomly placed, but they never cover a multiple of three or a number lower than six. If a player's roll reaches one of the Bowser Jr. spaces, Bowser Jr. rolls two dice instead of one and strikes the player with two hammers for that amount of damage. The player who delivers the final attack on Bowser Jr. earns an additional three points, and the player with the most points at the end of the minigame wins.

Ending
When Bowser Jr. is defeated, his Junior Clown Car short-circuits before it explodes, launching Bowser Jr. himself into space with a twinkle. Several Mini Stars then appear in Party Mode and Solo Mode.

In-game text

 * Rules – "Hit the Dice Blocks. The number that appears will light up segments of the gauge at the top of the screen. Light specific segments of the gauge to deal damage to Bowser Jr."
 * Controls – "Hold the Wii Remote vertically. Press to hit the Dice Blocks. You can make the Dice Blocks spin faster by shaking the Wii Remote."

Trivia

 * If one of the players reaches the "15" mark, that player will do their first-place animation instead of normally cheering. Also, their last attack will be a Ground Pound instead of a normal jump.
 * Likewise, if one of them lands on the "12" mark, they will do their second-place animation instead.
 * This is the only mid-boss battle not to play "Tough Enemy" and "Now You've Done It!"

Bowser Jr.s Würfelwut I dadi di Bowser Junior