Diddy Kong Racing DS Codes -

Adventure 2:
Complete the second Wizpig race in space and watch the credits. Adventure 2 will then be unlocked.

Opening the cracked wall:
At the start of the game, follow the track round until you go in a tunnel. In here, there is a cracked wall with a picture of Wizpig. Draw round Wizpig's head (ears included) and the wall should smash open. You must be quite accurate and it may take a few attempts.

Play as Drumstick:
Look for the mountain with the Frog Effigy. It is to the left of Wizpig's head. Use the stylus to pull back the frog and let go to release it. Try to launch it up to the Frog Effigy. When you do this successfully, a short intermission sequence will play and a new frog with a chicken head will jump out. Run this frog over to unlock Drumstick.

Play as Taj:
Collect all 47 balloons, have the full Wizpig Amulet, and get all gold trophies. After you have done this, go to Future Fun Land and start the final Wizpig Battle. Once you defeat Wizpig you will unlock Taj. 

Play as T.T.:
Beat all of T.T's times in Time Trial mode with every vehicle. You must also have the full T.T. amulet. You will see his ghost when you start the Time Trial. You must beat this. Once you defeat his ghost in every level, with every vehicle (including the unlockables), T.T. will be playable.

Play as Wizpig:
Complete Adventure 2 mode to unlock Wizpig. Like Taj, his stats look bad, but he is still good.