Instructions
Unlock Mii Character Outfit A
Select a 100cc Grand Prix race in the game menu.
Win third place or better in the 100cc Mushroom Cup and the 100cc Flower Cup to unlock the 100cc Star Cup.
Win third place or better in the 100cc Star Cup to unlock the 100cc Special Cup.
Win the 100cc Special Cup in first place to unlock the Mii character in Outfit A. This Mii can now be selected in the character menu at the beginning of the game.
Unlock Mii Character Outfit B
Choose time trial mode in the game menu.
Beat the ghost in each race by several seconds to unlock the fast ghost for that race.
Beat the fast ghost for all 32 races to unlock the Mii character in Outfit B. This Mii can now be selected in the character menu at the beginning of the game.