The following are known Action Replay Codes for Sports Illustrated for Kids: Baseball 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
be041c59
f9cae4dd
d10aa967
04b7e52f

Infinite Character Points
1852588b
5167d4b2

1 Ball for a Walk
41d014c6
9fbb2e5f

Never Strike Out
b77ca0ad
93deb00c

No Outs
c9b6a18a
0f5768bc

Home Team Score 99
5ac402c1
9f1203cc

Home Team Score 0
57ad699b
f2688418

Away Team Score 99
5ae7e96a
a4550c2a

Away Team Score 0
c3184a4f
0339ea67