Boss Rush is a gamemode in Mario Party 9 that allows the player to compete for points and beat all the bosses and mini bosses of Mario Party 9.
The players need to fight all 12 boss battles to exit. Once you get in, there's no way to exit until you fight all boss battles. After fighting all bosses, points are added depending to your rank in boss battles: five points for first, three points for second, two points for third and one point for fourth. Finally, Toad will announce the winner. Completing this mode gives you 10 party points.
List of Bosses In Order
|#||Name||Rules||Time limit||Phase 1 attack||Phase 2 attack|
|1||Sock it to Lakitu||Punch the blocks when Bullet Bills appear on them to launch attacks on Lakitu. The more Bullet Bills on the block, the bigger the attack!||N/A||Throws spike Koopas.||Throws bigger spike Koopas, take away two points each instead of one.|
|2||Wiggler Bounce||Ground-pound the segments of Wiggler's body to deal damage. The segments with the purple mark are worth one point, and the segment with the red mark is worth three.||N/A||Summon plants to attack you.||Wiggler moves faster.|
|3||Whomp Stomp||Players each choose 0 or 1 turns of the platform. Try picking a number that keeps you from winding up under Whomp! Players left standing can ground-pound Whomp for points!||10 seconds (to choose)||Smash a player below him.||Jump on the machine, each time add 1 turn of the platform.|
|4||Bombard King Bob-omb||Lob bombs at King Bob-omb! Bombs are thrown in order from left to right, and bigger bombs do more damage. Be careful: if two players or more select the same bomb, neither gets to throw it!||10 seconds (to choose)||Throws a bomb away (if there are less than 4 players), the player who select that bomb can't throw it.||Throws a bomb to attack players who can't throw a bomb.|
|5||Deck Dry Bones||Watch the cards. After they flip over, try to choose a card that matches the image of the platform Dry Bones is standing on.||5 seconds (to choose)||Throws a bone to players who choose a Bones card or choose nothing.||Switch cards in one column or one row before standing on a platform.|
|6||King Boo's Puzzle Attack||Line of three or more of the same item to launch an attack on King Boo. Line up lightning bolts for an extra powerful attack!||N/A||No attack, but if any of your rivals line up three lightning bolts you get -3.||Send a ghost, if it catches you, you need to shake the remote to get out.|
|7||Cheep Cheep Shot||Grab shells and fire them at Cheep Cheep as fast as you can while avoiding his attacks.||N/A||Mash to the front at the screen and hit players.||Jump out of water and jump down to hit players, so avoid his shadow.|
|8||Blooper Barrage||Blast Blooper with your cannon! Make sure you shoot down any Urchins that come flying your way!||N/A||Throws Urchins directly to you.||Sometimes he makes you hard to see him and the Urchins.|
|9||Spike Strike||Grab a hammer as fast as you can to knock the rolling Spiked Balls back at Spike! Gold hammers are worth three points, iron hammers are worth one, and branches aren't worth anything!||N/A||Throw Spiked Balls at players.||Magma comes closer.|
|10||Chain Chomp Romp||Watch the tracks, and choose a mine cart that will lead you to a cannon. Don't let your rivals get to the good carts before you! Gold cannons are worth three points, iron cannons are worth one.||10 seconds (to choose)||Bite player who come straight at him.||Two rails come straight at him instead of one.|
|11||Bowser Jr. Breakdown||Hit the Dice Blocks. The number that appears will light segments of the gauge at the top of the screen. Light specific segments of the gauge to deal damage to Bowser Jr.||10 seconds (to hit)||Light Bowser Jr. segments, he will summon two 1-2 Dice Blocks down and attacks you depends on those Dice Blocks.||There are three Bowser Jr. segments instead of one.|
|12||Bowser's Block Battle||Throw the dice! The more pictures of your character that show up on the dice, the more damage you'll do to Bowser. Be careful: if Bowser shows up on the dice, he gets to attack!||10 seconds (to throw the dice)||Attack you with the dice.||Throw his own dice down to summon any of his previous bosses, include himself.|