You can't!
You can't do so at all. R.O.B. is only available in the Mario Kart series in Mario Kart DS.
There are both Mario Kart and Mario Kart Solus games available. With any game, Solus simply means that the game comes with no peripherals.
not that i know of. just download an emulator
No. Mario Kart 7 is only available on the Nintendo 3DS
probably not
No, Mario Kart 64 isn't available for DSiWare. It is, however, available for the Wii's Virtual Console.
Wario is available in Mario Kart DS, but you don't need to unlock him. He's available to play from the start, as soon as you turn on the game.
It's available all around the world
The very first Mario Kart was released in 1992 on September 1st. Mario Kart is known for its multi-player racing that includes other Nintendo characters, the latest Mario Kart was released on December 7, 2011 and was named "Mario Kart 7".
You cannot unlock Baby Mario in Mario Kart DS. He is only in Mario kart: Double Dash!!! and Mario Kart Wii.
Yes it is since Mario Kart Double Dash is a Mario Kart game