Mario Kart Wii - More than one person can be the same character

Change Mii Racer weight class:
Go into the Mii Channel and change your Mii drivers weight, which will have an in game impact causing you to change weight class and have different vehicles.

Boost when recovering from a fall:
When you fall into something, such as water or falling from rainbow road, when you land, if you hit 2 at the moment you hit the ground, you get a temporary boost

Mirror mode:
Reach 1st place in all cups at 150cc class.

Alternate Title Screens and Ending photo:
Completing every single cup with a first place unlocks four new alternating Title Screens and one new Ending Photo.

Quick start:
Hold down "2" when 2 begins to fade for a quick boost.

Avoiding POW:
Just as the pow is about to strike, flick the wii wheel up as if doing a wheelie karts & bikes.

Golden wheel on WFC:
Use the wii wheel extensivly on all modes.

Profile name stars:
You can add a star next to your profile name on the results screen and the Wi-Fi races by completing all Grand Prix races with a certain rank.
One star profile name: Earn a "One Star" rank in all Grand Prix races.
Two star profile name: Earn a "Two Star" rank in all Grand Prix races.
Three star profile name: Earn a "Three Star" rank in all Grand Prix races.

Unlockable bikes:
Bubble Bike small bike: Win Mirror Leaf Cup.
Dolphin Dasher medium bike: Win Mirror Star Cup.
Magikruiser small bike: Play Time Trials on 8 different courses.
Nitrocycle medium bike: get at least 1 Star Rank for all 100cc Wii Grand Prix Cups.
Phantom large bike: Win Mirror Special Cup.
Quacker small bike: Win 150cc Star Cup.
Rapide medium bike: Win 100cc Lightning Cup.
Torpedo large bike: Unlock 12 Expert Staff Ghost Data in Time Trials.

Unlockable karts:
Aero Glider large kart:get at least 1 Star for all 150cc Retro Grand Prix Cups.
B Dasher Mk 2 Medium Kart: Unlocked 24 Expert 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.
Dragonetti large kart: Win 150cc Lightning Cup.
Piranha Prowler large kart: Win 50cc Special Cup.
Rally Romper small kart: Unlock 1 Expert Staff Ghost Data in Time Trials.
Royal Racer medium kart: Win 150cc Leaf Cup.
Turbo Blooper medium kart: Win 50cc Leaf Cup.

Unlockable chracters:
King Boo: Beat the Star Cup at 50cc.
Diddy Kong: Beat the lightling cup at 50cc.
Baby Daisy: Get at least a 1 Star ranking in all the Wii Grand Prix Cups at 50cc.
Dry Bones: Beat the Leaf Cup at 100cc.
Mii Character: Beat the Special Cup at 100cc.
Bowser Jr.: Get at least a 1 Star ranking in all the Retro Grand Prix Cups at 100cc.
Daisy: Beat the Special Cup at 150cc.
Dry Bowser: Get at least a 1 Star ranking in all the Wii Grand Prix Cups at 150cc.
Birdo: Either play on 16 different courses in Time Trial mode or finish ahead of a total of 250 players online.
Rosalina: You will need to have a Super Mario Galaxy save file on your Wii and the game will award you with this character after playing around for a bit. It seems you can unlock it too by getting at least a 1 star ranking in all of the mirror cup.
Toadette: Play on all 32 courses in Time Trial mode.
Funky Kong: In Time Trial mode, unlock 4 Expert Staff Ghost Datas.
Baby Luigi:In Time Trial mode, unlock 8 Expert Staff Ghost Datas.
Mii Character Mario Costume : In Time Trail mode, unlock all 32 Expert Staff Ghost Datas.

Unlockable trophies:
Star Cup: recieve a trophy on the Mushroom Cup and Flower Cup.
Leaf Cup: recieve a trophy on the Shell Cup and Banana Cup.
Special Cup: recieve a trophy on the Star Cup.
Lighting Cup: recieve a trophy on the Leaf Cup.