The following are known Action Replay Codes for Tweety & The Magic Gems on Nintendo Game Boy Advance (GBA).
These codes were also known as GameShark Codes and in most cases will work on both devices.

These codes are for the U.S. version of the game.

Master Code – Must Be On
c8acfe74
f34031eb
6a11d778
be902827

Max Character Points
777d8c8f
ea411269
0b4a9a3b
394b19cd

Have Red Gem
b4e660c7
4225f4bb

Have Blue Gem
248ef2d6
5cca7e5c

Have Green Gem
47ae9a5b
7b31a1e1

Have Yellow Gem
90402c06
24a81432

Have Purple Gem
2ea86dc9
5505c9e4

Press AR Button: 10 Moves
692fb40a
d9da3abd
d95b49b6
085cec44