The following are known Action Replay Codes for Classic NES Series: Castlevania 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
f9c623db
8c533433
0ccba5da
6d52de7b

Infinite Health
911c5cb2
9e128276

Invincible
568135a4
39e68a4b

Infinite Hearts
f38a0e2c
08ba5336

Infinite Time
3f5c70b5
6ab6aa77

Have Best Whip
c6e9472b
2b89448b