To unlock mini-games, you must complete the following amount of objectives.

Mini game	How to unlock
Attack: Finishing Moves	Complete 20 objectives.
Attack: Ground Pound	Complete 50 objectives.
Minigame: Bumper Carts 1	Complete 15 objectives.
Minigame: Bumper Carts 2	Complete 45 objectives.
Minigame: Race Track 1	Complete 25 objectives.
Minigame: Race Track 2	Complete 60 objectives.
Minigame: Range Driver 1	Complete 10 objectives.
Minigame: Range Driver 2	Complete 40 objectives.