Ok well in order to un-lock anything you just have to race race race. The more you race the more people/karts you un-lock. In order to un-lock courses you have to get a good overall score in the other cups of that level. Just keep playing!
You can't, because that track isn't in Mario Kart DS. It is, however, in Mario Kart 7, which was the first game to have retro Rainbow Road tracks.
To get 36 karts on "Mario Kart DS", you have to come in first on every race and cup.
Retro cups are the old Mario Kart races. Example:N64 Mario Raceway,DS Delfino Square,GCN Waluigi Stadium. The retro cups are "The Shell cup","The Banana cup","The leaf cup",and"The Lighting cup". The Mushroom cup,Flower cup,Star cup,and the Special cup,are NOT Retro cups,they're new.
The Mushroom, Flower, Star, or Special Cup.
complete the 2nd cup on 100cc
Win a grand prix
mushroom cup luigi circuit moo moo meadows mushroom gorge toad's factory flower cup Mario circuit coconut mall dk's snowboard cross wario's gold mine star cup daisy circuit koopa cape maple treeway grumble volcano special cup dry dry ruuins moonview highway bowser's castle rain bow road shell cup peach beach (Mario kart: double dash!!) Yoshi falls (Mario kart ds) ghost valley 2 (super Mario kart) Mario raceway (Mario kart 64) banana cup sherbet land (Mario kart 64) shy guy beach (Mario kart super circuit) delfino square (Mario kart ds) waluigi staduim (Mario kart: double dash!!) leaf cup desert hills (Mario kart ds) bowser castle 3 (Mario kart: super circuit) d.k.'s jungle parkway (Mario kart 64) Mario circuit (Mario kart: double dash!!) lightning cup Mario circuit 3 (super Mario kart) peach gardens (Mario kart ds) dk mountain (Mario kart: double dash!!) bowser's castle (Mario kart 64)
Yes there is Mario kart for ds. It is called Mario Kart DS. You should buy it immediately.
Beat the mushroom and flower cup dummy.
It's the Mushroom Cup, always is.
Beat 150cc Special Cup.
Mario Kart DS happened in 2005.