Fairly OddParents: Shadow Showdown Cheats (GameBoy Advance)

Enter XGT8QL as a password. When you get to the part of carrying bananas to two monkeys,
distract the second one, bust open the crate behind him by holding B, and run into it.
There should be a horseshoe in the same location as the crate. Walk over it to get an
extra life. You can do this as many times as desired.

Enter SBM2S6 as a password to start falling getting stars. 

Enter the following passwords to start at various points in the game:

JBR!S6

SLRZQL

JQR2SN

DLC2S6

NBR2SN

NGH2S6

NBC2SN

SG12QL

GJ?4L6

Enter S8MXS6 as a password to start at about the middle of the game.