Mario Kart DS (U) +8 Trainer by cracker

It includes:
Nitro Courses Unlocked
Retro Courses Unlocked
All Characters Unlocked
All Cars Unlocked
All Classes Unlocked
Play As Shy Guy (Hold L+R+A while loading)
Play As R.O.B. (Hold L+R+B while loading)
Always Have Super Mushroom

Note: Extract the contents of the zip to a folder along with your game 
and Xdelta 
(http://www.cheaters-heaven.com/component/cheaters/38990/PC/xdelta-command-line-tool.html)
or (http://evanjones.ca/software/xdelta.exe) then run cr-mkdsp8.bat