By getting good trophy's on the cups, you can unlock more.
yes.
if it is the same price
You don't
you dont
Nintendo.
No, Mario Kart can only connect to other DS systems.
you cant
No it is not but some people think it is for some crazy reason.
It is a tie of Nintendogs, Animal Crossing, and Mario Cart.
There is no baby Yoshi on Mario cart ds, all that i know. Because I have passed it all and there is no baby Yoshi in the game of ds.
for ds lol game and Mario cart game!
you have to beat the 100cc grand prix