Mii

Miis are characters made on the Wii that look like 3D humans. There is a Wii Channel devoted to making them, called the Mii Channel. They can be created whenever the player wants, using different head, body, eye, hair, mouth, nose, and glasses types. Up to 100 Miis can be stored on a Wii and ten per each Wii Remote. The main purpose of Miis is to be an avatar of the creator, but are used to a wider extend. Miis are compatible with Mario Kart Wii. They can be any size, depending on their height and weight. This makes them the most versatile characters. However, Miis are only middleweights in Mario Kart 7. Miis must be unlocked. The Mii's voice also varies depending on the color their shirt is. Also, Miis from your Mii plaza sometimes appear in the crowd, or on statues in some tracks. Miis have two outfits: Mii Outfit A and Mii Outfit B.

Mii's Stats
The Mii's have four stats simliar to Baby Peach, Mario and Donkey Kong but depends on the weight of their class will give different stats in Mario Kart Wii but however the Large Mii is the only character in the game to only have 5 stats thus granting them somewhat of a special advantage, However in Mario Kart 7 the Mii's are under as Medium Weight class along with Mario and Luigi.

Small Mii (Mario Kart Wii)
The Small Mii can work with any Kart or Bike in their class but they are best suited if using the Bullet Bike, Booster Seat, Tiny Titan, or Mini Beast (Concerto)
 * Speed: 3
 * Weight: 3
 * Drift: 3
 * Mini-Turbos: 3

Medium Mii (Mario Kart Wii)
The Medium Mii can work with any Kart or Bike in their class but they somewhat useful using such as the Sugarscoot (Bon-Bon), Classic Dragster, Daytripper, Zip-Zip (Rapide), Super Blooper (Turbo Blooper) and Dolphin Dasher.
 * Speed: 3
 * Weight: 3
 * Off-Road: 3
 * Mini-Turbos: 3

Large Mii (Mario Kart Wii)
The Large Mii can work with Karts and Bikes in their class, since they are the only characters to have 5 stats in the game but they can outshine a few large characters in terms of what kart nor bike they are using but is outrivaled by likes of Baby Daisy, Baby Luigi, Daisy, Rosalina and Funky Kong.
 * Speed: 3
 * Acceleration: 3
 * Handling: 3
 * Drift: 3
 * Mini-Turbos: 3

Mii (Mario Kart 7)

 * Class: Medium
 * Speed: 3.5
 * Acceleration: 3
 * Weight: 3.25
 * Handling: 2.75
 * Off-Road: 3.75

Mii Outfit A
Mii Outfit A is unlocked by clearing the 100cc Special Cup.