Why Unlock Characters?
Personal preference isn't the only factor in choosing a kart driver. Each character is better than others for different reasons. Mario's standard kart is faster than Wario's, yet Wario can hit harder than Mario because he's heavier. Consider each stat when choosing a character.
Although Mario Kart Wii comes with 12 default characters right from the start, work to unlock 13 hidden characters. This will allow you better stats, interesting personalities and fun karts.
As you play through the game, you may find yourself unlocking new characters without even trying. Some characters are unlocked by getting a good grade on races while others unlocke when you beat a certain number of wifi matches. Here is a comprehensive list of how to unlock all hidden characters in Mario Kart Wii.
Baby Daisy: Unlock the baby version of Daisy by getting a 1 star grade or higher in all of the 50cc Wii-cups.
Baby Luigi: Unlock eight expert staff ghosts in Time Trial mode to get Baby Luigi.
Birdo: There are two ways to unlock Birdo. Either win 250 wifi matches or play Time Trial mode on 16 different courses.
Bowser Jr.: Unlock Bowser's young son as you get a 1 star or better driving rating on the 100cc Retro-cups.
Daisy: Unlock grown-up Daisy by winning the 150cc Special Cup.
Diddy Kong: Get first place in all of the 50cc cups to get Diddy Kong.
Dry Bones: Finish first place in the 100cc Leaf Cup to unlock Dry Bones.
Dry Bowser: Dry Bowser unlocks when you get a 1 star rating on all of the Wii-cups in 150cc.
Funky Kong: Unlock four of the expert staff ghosts in Time Trial mode.
King Boo: Finish first place for the 50cc Star Cup to get spooky King Boo.
Rosalina: First, you need to have a save file from Super Mario Galaxy on your Wii. Once you do, you have two ways to unlock Rosalina. You can either get a 1 star rating in all of the Mirror Mode Cups, or she will be unlocked automatically when you go through 50 races.
Toadette: Unlock the female equivalent to Toad two ways. Either win 1000 wifi matches or play all 32 courses in Time Trial mode.
Unlocking Your Mii
In addition to unlocking characters from the Nintendo franchise, you can also unlock the ability to use your Mii character in Mario Kart Wii. Unlock your Mii by placing first in the 100cc Special Cup. You can unlock your Mii in another outfit by unlocking all of the 32 expert staff ghosts in Time Trial mode. Once you’ve unlocked the Mii, you drive the karts and bikes as your virtual representation rather than a traditional Nintendo character.