Embarassingly, it's not because I've unlocked them all myself, most of my time with Mario Kart has been played online, but over at British Gaming Blog they have a complete character list up. Full list of selectable and unlockable characters after the jump.

Mario Kart DS Full Character List [British Gaming Blog]

Mario
Luigi
Peach
Donkey Kong
Bowser
Wario
Toad
Yoshi
Shy Guy
Daisy
Waluigi
Dry Bones
Koopa Troopa
Toadette
Petey Piranha
R.O.B.

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