In order to unlock the locked Battle Games, you must complete the game at the highest available difficulty. In order to unlock a new Battle Game, such as Flag Competition, you have to complete the hardest level of the game before it (in this case, complete Battle Competition at hard to open Flag Competiton). To unlock Donkey Kong as a driver, beat him in any Super Duel competition on hard difficulty. There are also some locked machine parts. If you beat DK in any hard Super Duel competition, you unlock the DK Body, DK Engine, DK Tires, and DK Weapon. If you beat all three games in all three difficulties, you unlock the Skolar Body, Skolar Engine, Skolar Tires, and Skolar Weapon. After you purchase all 44 machine parts, Bob-omb Wall and Bowser Punch become unlocked.

To unlock Bowser's Nightmare, beat the Story Mode.

To unlock Frightmare, beat Bowser's Nightmare in Story Mode.

To unlock the Hard difficulty setting for an indiviudal game type, beat the game on Normal.

To unlock Intense Mode, beat the Story Mode on Normal.

Once you play a mini-game in Story Mode or Party Mode, it becomes unlocked. In Mini-Game Mode, to play Mini-Game Circuit, you have to have unlocked one four player game, one 2 vs. 2 game, one 1 vs. 3 game, and one duel game. In order to play Mini-Game Decathlon in Mini-Game Mode, you have to have unlocked Chomp Romp, Dinger Derby, Flower Shower, Ground Pound, Hydrostars, Later Skater, Leaf Leap, Night Light Fright, Triple Jump, and Will Flower.

In the Bowser mini game where he lights the fire works and it rains fire down on the characters, there is always a safe spot on the bottom edge of the circular platform. Just run to it and avoid the sparks every time.