Just keep playing the grand prix until you unlock something. I've memorized a few unlocking formulas, so here they are:
To unlock the Star Cup: Get at least 3rd place or betterin the Mushroom and Flower Cup.
To unlock Dry Bones: Unlock the 100cc Leaf Cup.
To unlock Daisy: Win the 150cc Special Cup. (Win the Star Cup 150cc to win the Special Cup 150cc)
To unlock the Leaf Cup: Win the 100cc Banana Cup.
To unlock the Lightning Cup: Win the 100cc Leaf Cup.
That's all I know for now. I hope this answered your question! :)
By Beating cups
When you hack the game.
Get gold trophy in grand prixs to unlock karts and characters.
They Are Exactly the same cups in the same order as Mario Karts DS
You do an amount of races or you can finish cc's.
by getting good times on each track.
That's completely opinion based.
Pressing the + button.
King Boo, Bowser, Dry Bowser, Rosalina, and Funky Kong all use large karts on Mario Kart Wii.
Karts. It can have longer turbo boosts.
No there is not another mode after mirror mode
you have to complete certain things to unlock stuff. this website shows you how to unlock everything, including karts. http://www.videogamesblogger.com/2008/04/18/how-to-unlock-all-mario-kart-wii-secret-characters-bikes-karts-and-more-guide.htm