if your talking about Mario Kart ds you cant if your talking about Mario kart wii I don't know:(
In Mario Kart DS, there is no mission 8.
You can't, he's not in Mario Kart DS. However, you can get him in Mario Kart Wii, Mario Kart 7, and Mario Kart 8, and Mario Kart 8 Deluxe.
To Unlock Baby Luigi you have to unlock 8 Expert Staff Ghost Data in Time Trials.
It's a bit complicated.You have to unlock 8 staff ghosts.
To unlock baby Luigi, you must unlock 8 Expert Staff Ghost Data in Time Trials.
No, Mario Kart 8 is only for the Wii U.
Metal Mario Does Not Appeared in Mario Kart Wii, How Ever, He is a Playable on Mario Kart 7, 8, and Tour
First, you have to unlock the Mirror Mode of the Mario Kart game by winning all the 150cc cups with gold. Then, you have to unlock the Lightning Cup. By unlocking and winning the Mirror Lightning Cup in Gold, you can unlock the Blue Falcon. It's good you asked, because the Blue Falcon is an amazing kart. It is very fast. (Just try not to go offroad with it)
Unlock 8 expert staff ghosts in Time Trials mode.
You unlock Baby Luigi by unlocking 8 Expert Staff Ghost Data in time trials.You unlock him by unlocking 8 expert staff ghost data, but you can also win 100 NWFC ghosts races. and of course being good at Mario kart !
unlock 8 fast staff ghosts or beat 100 ghosts (your choice)
Mario Kart 8 will be released on May 30, 2014
Yes, you can use your Mii in Mario Kart 8