Rosalina and Birdo are the only 2 Characters in the game to have 2 ways of unlocking them, Rosalina: (Easy) Have a save File In Super Mario Galaxy on your Wii-(Hard) Get a Star Rank in all of the Mirror cups. To Unlock Most Of the Characters, You need to Get a fast staff ghost in time trials (Beating the Normal Staff Ghost by a certain amount of time (Time may vary, Depending on Coarse) and by Winning A star rank/ Getting First in Grand Prix mode.

The heavyweight ones are Wario, Waluigi, Donkey Kong, Bowser, King Boo, Rosalina, Funky Kong and Dry Bowser. The mediumweight ones are Mario, Luigi, Peach, Daisy, Yoshi, Birdo, Diddy Kong, and Bowser Jr. The lightweight ones are Baby Mario, Baby Luigi, Baby Peach, Baby Daisy, Toad, Toadette, Koopa Troopa, and Dry Bones. They are divided into three groups: lightweight, mediumweight, and heavyweight. The characters all have different stats and abilities.

Characters are the people and animals you can play as in Mario Kart Wii.