How to Unlock Leaf Cup on Mario Kart Wii: 12 Steps (with Pictures)
Safely Unlocking Your Wii with NO Modchip! (Works with System Menu 4.2+ out of the box) Installing Homebrew Applications and Games… | Wii console, Wii, Wii u games
Mario Kart – Wii: How to Unlock Funky Kong
How to unlock all Mario Kart Wii secret characters. Cheats for bikes, karts and more (guide) - Video Games Blogger
Decided to make a Mario Kart Wii unlockables infographic since there didn't seem to be one. Hope it comes in handy :) : r/mariokart