Diddy Kong Racing DS Cheats

Unlock the Secret Characters
There are 4 hidden characters that can be unlocked:

Drumstick: Fling a frog up to the green sillouette shaped frog picture in the world map (To the left of Wizpigs face). Stomp on the frog that comes out.
T.T: Beat all of his ghosts in Single Player Race. It DOESNT include the new unlockable stages.
Taj: Complete Adventure 1.
Wizpig: Complete Adventure 2.

Super Boost
Before landing on a zipper or using a blue balloon, let go of the acceleration button to get a much stronger longer lasting boost then normal.

Answers to sand puzzle
Near the lighthouse, theres a location where you can use the stylus to draw puzzles in the sand. If you draw a balloon, you'll get a golden balloon. If you draw a pentagon, you'll get a scratch card. If you draw a coin (small circle shape) you can get 10 coins, but you can do this up to four times.

Unfreeze the balloon
In the ice area of the overworld map theres a balloon stuck in a block of ice. Using the DS's touch screen pad, you can slide it down into the water to unfreeze it, then follow it down the river to the beach where it melted to collect it.