The following are known Action Replay Codes for Buffy the Vampire Slayer: Wrath of the Darkhul King 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
c444b724
877f8361
e326e95e
6175058f

Infinite Health
ef376477
510a78ed

Infinite Lives
2bb18015
ade275d7

Infinite Stakes
c3299856
058c58e7

Infinite Mops
e2495216
7179f690

Infinite Daggers
34ee774d
f2b79c1b

Infinite Axes
c9ddd1d5
1c813336

Infinite Flame Thrower
c2b10f6c
3eed93db

Infinite Bats
0474eb95
41aa8b68

Infinite Crossbow
64bbc05a
b1f56b64

Infinite Laser Rifle
86462118
3b5223df

Infinite Crosses
23a3e383
55bdf424

Infinite Holy Water-S
022d4331
9e0295db

Infinite Holy Water-L
505ae647
3dc616c0

Infinite Battery-S
21457f32
36f3b7ad

Infinite Battery-L
472dc08a
b7c01e70

Infinite Torch
476ff2d5
86daad2b

Glove of Myhnegon
8ea408be
b964b938

Max All Weapons
11664bbd
ded1b1b2
4eead3ca
6f7b35d7