What are all the Mario cart characters

Well, here are all the ones you can unlock and how to unlock them:

Baby Daisy Get a "One Star" rank or better in all 50cc cups. Alternately, win 1,950 races.
Baby Luigi Unlock eight Expert Staff Ghosts in Time Trials mode. Alternately, win 3,150 races.
Birdo Play 16 different courses in Time Trials mode. Alternately, get 250 Wi-Fi wins or win 1,350 races.
Bowser Jr. Get a "One Star" rank or better in all 100cc Retro Cups. Alternately, win 3,450 races.
Daisy Win the 150cc Special Cup. Alternately, win 2,850 races.
Diddy Kong Successfully complete all 50cc Retro Cups. Alternately, win 450 races.
Dry Bones Win the 100cc Leaf Cup. Alternately, win 1,050 races.
Dry Bowser Get a "One Star" rank or better in all 150cc Wii Cups. Alternately, win 4,350 races.
Funky Kong Unlock four Expert Staff Ghosts in Time Trials mode. Alternately, win 2,250 races.
King Boo Win the 50cc Star Cup. Alternately, win 750 races.
Mii (Outfit A) Win the 100cc Special Cup. Alternately, win 1,650 races.
Mii (Outfit B) Unlock all 32 Expert Staff Ghosts in Time Trials mode. Alternately, win 5,100 races.
Rosalina Get a "One Star" rank or better in the Wii Cup Series. Alternately, have a saved game file from Super Mario Galaxy and win 50 Grand Prix races; or win 4,950 races.
Toadette Play on all 32 courses in Time Trials mode. Alternately, get 1,000 Wi-Fi wins or win 2,550 races. I can't remember all the ones that are already unlocked, but if you have the game you probably know already:).