This code gives you a 999 rare candy in Pokemon Diamondl! Here’s the code:

94000130 fcff0000
b21c4d28 00000000
b0000004 00000000
00000dac 03e70032
d2000000 00000000

Warning - It replaces whatever you have in the first part of your medicine pocket

You can buy an Action replay here. They are definitely worth it: