Here are some Gameshark codes for Yu-Gi-Oh! Forbidden Memories:
Win Duel Immediately (duel result flag)
F00AF21C F3F0 800AF21C 3042
Almar's Guides lists these as 801D07E0 423F and 801D07E2 000F . Yu-gi-oh Forbidden Memories Gameshark Codes
Lets you buy cards from the in-game shop without limit. Here are some Gameshark codes for Yu-Gi-Oh