Mario Kart Wii/Unlockables

Circuits

 * Star Cup: get a silver trophy (second place) or better on Mushroom Cup and Flower Cup.
 * Leaf Cup: get a silver trophy (second place) or better on Shell Cup and Banana Cup.
 * Special Cup: get a silver trophy (second place) or better on Star Cup.
 * Lightning Cup: get a silver trophy (second place) or better on Leaf Cup.

Characters

 * King Boo: get a silver trophy (second place) or better on Mushroom Cup, Flower Cup, Shell Cup, and Banana Cup.
 * Diddy Kong: get a gold trophy (first place) or better on all 50CC circuits, or complete 450 races.

Karts

 * 50CC Bikes: get a silver trophy (second place) or better on all eight 50CC circuits.