
There are 14 secret characters in Mario Kart Wii that can be unlocked. Below is a list of characters to unlock the form.
1. Birdo: You have to play 16 different courses in Time Trial mode
2. Daisy Baby: Play all the 50cc cups and get at least a "One Star" rank in all
3. Bowser Jr.: Play all 100cc Retro Cups and get at least a "One Star" rank in all
4. Diddy Kong Complete all 50cc cups
5. Dry Bowser: Play all 150cc cups and get at least a "One Star" rank in all
6. Daisy: Get first place in the 150cc Special Cup
7. Dry Bones: Get first place in the 100cc Leaf Cup
8. Baby Luigi: First unlock expert staff data...