Mario Kart: Double Dash!!/Unlockables

In the GameCube game Mario Kart: Double Dash!!, there are karts, characters, and even courses you can unlock.
 * Note: You must obtain a gold trophy in the listed event to unlock the bonus object.

Mushroom Cup

 * 50cc: Green Fire (kart)
 * 100cc: Rattle Buggy (kart)
 * 150cc: Luigi's Mansion (battle stage)
 * Mirror mode: Toadette Kart (kart)

Flower Cup

 * 50cc: Bloom Coach (kart)
 * 100cc: Waluigi Racer (kart)
 * 150cc: Turbo Birdo (kart)
 * Mirror mode: Tilt-a-Kart (battle stage)

Star Cup

 * 50cc: Para Wing (kart)
 * 100cc: Special Cup (cup)
 * 150cc: Barrel Train (kart)
 * Mirror mode: King Boo and Petey Piranha (character combo), Piranha Pipes (kart)

Special Cup

 * 50cc: Bullet Blaster (kart)
 * 100cc: Toad and Toadette (character combo), Toad Kart (kart)
 * 150cc: All Cup Tour (cup)
 * Mirror mode: Boo Pipes (kart)

All Cup Tour

 * 50cc: Nothing
 * 100cc: Nothing
 * 150cc: Mirror mode (engine size)
 * Mirror mode: Parade Kart (kart)

Once you win every cup, you get a new "Thanks For Playing" screen and a new title screen.