So the last character roster was fake, but this time, it's real. And I have PROOF! Here is the character roster, and then scroll further down for proof:

Baby Mario
Baby Luigi
Baby Peach
Baby Daisy
Toad
Toadette
Koopa Troopa
Dry Bones
Mario
Luigi
Peach
Daisy
Yoshi
Birdo
Diddy Kong
Bowser Jr.
Wario
Waluigi
Donkey Kong
Bowser
King Boo
Rosalina
Funky Kong
Bowser Bones

PROOF:

The Unlockables so far **HUGE SPOILERS** - Mario Kart Wii Forum - Mario Kart Wii Dicussion