Every unlockable is on the bottom of the yugioh card itself. They are 8 digit numbers that unlock those cards. To post all of them would take too much space. Look on wikipedia for pictures of the cards. Here are a couple good cards to start you off:
44095762 Mirror Force
62279055 Magic Cylinder
75830094 Horus Lv.4
11224103 Horus Lv.6
48229808 Horus Lv.8
Chat with our AI personalities
go to new game and press start!!..
i have the game and I'm pretty sure there is no way to get them.
either trade from nightmare troubadour or use an action replay (don't know the code though)
you need to win at lest 50 duels in free duel mode
Neither the card nor the duelist are avalible in 2007. Strangly the duelist is but not the card in 2008. You can unlock her (yes, it's a she) by clearing the Phantom of Chaos Armytile stone challenge in the World of Chaos.