DS cheats

Game=
Mario kart
cheats

characters
 Daisy = get a gold trophy on every cup in retro grand prix on 50cc

Dry bones = get a gold trophy on every cup in nitro grand prix on 50cc

Waluigi = get a gold trophy on every cup in retro grand prix on 100cc

items
3rd kart for all characters = get a gold trophy on every cup in nitro grand prix on 100cc

Choose from 7 karts for each character = get a gold trophy in every cup in nitro grand prix on 150cc

Choose from any kart for each character = get a gold trophy in every cup in the grand prix on 150cc mirror that you dindn't use to unlock R.O.B.

unlockables
Unlock R.O.B. as a racer = Finish 150cc mirror mode class with gold trophies on all cups
 
Unlock mission 7 in mission mode = get at least a 1-star ranking on all levels of every mission in missions level 1-6

150cc miror mode = finish 150cc retro class with gold trophies in every cup.