Use these cheats to get bonuses:
Bloom Coach: win the Flower cup at 50 cc to unlock Daisy's kart.
Green Fire: win the mushroom cup at 50 cc to unlock Luigi's kart.
Battle Buggy: win the Mushroom cup at 100 cc to unlock Baby Luigi's kart.
Waluigi Racer: win the Flower Cup at 100cc to unlock Waluigi's kart.
Turbo Birdo: win the Flower cup at 150 cc to unlock Birdo's kart.
Bullet Blaster: win the special cup at 50 cc.
Para Wing: win the Star cup at 50cc.
Toad and Toadette Duo: win the special cup at 100 cc to unlock these two characters.
Luigi's Mansion Battle Stage: win the Mushroom cup at 150 cc to unlock this extra stage for multiplayer battle.
Special Cup: win the Mushroom, Flower, and Star Cups at 100cc.
Grand Slam Cup: win the Mushroom, Flower, Star, and Special Cups at 150cc.
All Cup Tour: win all cups at 150cc.