Boss Battle Space

A Boss Battle Space is a space that appears twice on each board in the game Mario Party 9. This space disregards how many spaces the current Captain is able to go because it always stops the current Captain whenever this space is passed (similar to a Captain Event Space). Whenever this space is passed/landed on, a Boss Minigame triggers. This space later returns in Mario Party 10.

Mario Party 9
The first Boss Battle Space usually appears in the first third or half of the board, outside a fort. Here, Bowser Jr. will taunt the players and force them to fight the miniboss of the area (or allow the captain to choose a miniboss, if playing Party Mode). The players often encounter a new element of the stage after beating the boss here.

The second Boss Battle Space always appears at the end of the board, marked by a Bowser Gate. When players reach the gate, they will emerge from their vehicle and be confronted by Bowser himself. As with his son, the Koopa King will force players to play a boss minigame (although he lets the captain pick in Party Mode). After the boss is defeated, the final results are produced and the Superstar is named.

The Boss minigame triggered at any given Boss Battle Space depends on the board in Solo Mode. In Party Mode, the Captain is able to choose from three boss minigames, usually including the one that would normally occur on the space in Solo Mode.

However, in Bowser Station, the mid-boss is always Bowser Jr., while the stage boss is always Bowser. Likewise, in DK's Jungle Ruins, Diddy Kong is always the mid-boss, while Donkey Kong is always the stage boss.

Mario Party 10
In this game, Boss Battle Spaces will appear at a Fortress where the miniboss will be battled. They will also appear at a Castle where the end-stage boss will be battled.

The first time a board is played, the game automatically select the boss of the corresponding board. When the board is played again,the Captain chooses between 3 choices like in Mario Party 9 for the miniboss and the player in last position chooses between 3 choices for the final boss.

There isn't any "Captain Bonus" anymore in the end of the minigame. Instead, the player who stop on this space will win a set of Mini Stars (5 for the Fortress and 10 for the Castle).