After meeting the requirements, some unlockables may require you to back out of your save file and reselect it. Note: In different countries, the karts have different names but the unlocking methods are the same.

Kart	How to unlock
Aero Glider (large kart)	Attain at least 1 Star in all 150cc Retro Cups.
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.
Sprinter (Medium Kart)	Unlocked 24 Expert Staff Ghosts.
Tiny Titan (small kart)	Beat 50 opponents during Wi-Fi play or unlock one expert staff ghost.
Turbo Blooper (medium kart)	Win 50cc Leaf Cup.