characters

King Boo---Win 50cc Star Cup
Diddy Kong---Complete retro 50cc Cups
Baby Daisy---1 Star in all 50cc Wii-Cups
Dry Bones---Win 100cc Leaf Cup
Mii (Outfit A)---Win 100cc Special Cup
Bowser Jr.---1 Star in all 100cc Retro-Cups
Daisy---Win 150cc Special Cup
Dry Bowser---1 Star in all 150cc Wii-Cups
Rosalina---Have a Super Mario Galaxy savefile and she will be unlocked after 50 races or get 1 star in all Mirror Mode Wii-Cups
Funky Kong---Unlock 4 FAST Staff Ghost Data in Time Trials
Baby Luigi---Unlock 8 FAST Staff Ghost Data in Time Trials
Birdo---Play Time Trials on 16 different courses OR win 250 Wi-Fi matches.
Toadette---Play Time Trials on all 32 different courses or win 1000 Wi-Fi matches.
Mii (Outfit B)---Unlock all 32 FAST Staff Ghost Data in Time Trials


Karts

Aero Glider (large kart)---Attain at least 1 Star in all 150cc Retro Cups
Sprinter (Medium Kart)---Unlocked 24 FAST Staff Ghosts
Blue Falcon (small kart)---Win Mirror Lightning Cup
Cheep Charger (small kart)---Attain at least 1 Star Rank for all 50cc Retro Grand Prix Cups
Honeycoupe (large kart)---Win 150cc Lightning Cup
Piranha Prowler (large kart)---Win 50cc Special Cup
Royal Racer (medium kart)---Win 150cc Leaf Cup
Turbo Blooper (medium kart)---Win 50cc Leaf Cup
Tiny Titan (small kart)---Beat 50 opponents during Wi-Fi play or unlock one expert staff ghost

Bikes

Quacker (small bike)---Win 150cc Star Cup
Bubble Bike (small bike)---Win Mirror Leaf Cup
Magikruiser (small bike)---Play Time Trials on 8 different courses
Zip Zip (medium bike)---Win 100cc Lightning Cup
Sneakster (medium bike)---Attain at least 1 Star Rank for all 100cc Wii Grand Prix Cups
Dolphin Dasher (medium bike)---Win Mirror Star Cup
Shooting Star (large bike)---Win 100cc Star Cup
Phantom (large bike)---Win Mirror Special Cup
Spear (large bike)---Unlock 12 FAST Staff Ghost Data in Time Trials