Yu-Gi-Oh - The Dawn of Destiny:
Free Rare Cards:
Enter the following names to receive the corresponding cards. 

Tri-Horn Dragon Card: GOD OF CARDS
Cosmo Queen Card: KONAMI 
Zera the Mant Card: XBOX 

Get Rare Cards: 

Card Name - How to Get 

Dark Necrofear: 
Duel Odion and pick the Obelisk Statue /or/ Duel Bakura and pick the Ra or Slifer statue. 

Valkyrion the Magna Warrior: 
Duel Yami Yugi and sacrifice Beta, Gamma and Alpha to put it in play and pick the Ra /or/ Slifer statue. 

Exodia Set: 
Duel Rare Hunter /or/ Grandpa and pick the Slifer and Obelisk statues.
Mirror Force: 
Duel Yami Yugi /or/ Joey and pick the Ra and Slifer statues. 
Jinzo: 
Duel Joey and pick the Slifer statue.
Magic Cylinder: 
Duel Kaiba and pick the Slifer statue. 
Red-Eyes Black Dragon: 
Duel Joey and pick the Obelisk statue. 
Summoned Skull: 
Duel Yami Yugi and pick the Obelisk /or/ Slifer statue. 
B. Skull Dragon: 
Duel Joey and pick the Obelisk statue. 
Polymerization: 
Duel Pegasus and pick the Obelisk statue. 
Gaia the Fierce Knight: 
Duel Yami Yugi and pick the Obelisk statue. 
Cyber Stein: 
Duel Marik in a Triple or Single duel and pick the Slifer statue. 
Pot of Greed: 
Duel Grandpa and pick the Slifer statue. 
Swords of Revealing Light: 
Duel Rare Hunter and pick the Slifer /or/ Obelisk statue. 
Card Destruction: 
Duel Yami Bakura and pick the Obelisk statue. 
Axe of Despair: 
Duel Yami Yugi and pick the Obelisk statue /or/ Duel Kaiba and pick the Slifer statue. 
Monster Reborn: 
Duel Kaiba and pick the Slifer Statue /or/ Duel Joey and pick the Obelisk statue.
Tribute to the Doomed: 
Duel Yami Bakura and pick the Slifer statue.
Change of Heart: 
Duel Yami Bakura and pick the Ra statue.
Delinquent Duo: 
Duel Arkana and pick the Obelisk statue.
Dark Hole: 
Duel Yami Bakura and pick the Slifer statue.

Use Opponent's Decks:
Beat every opponent in triple duel mode and hold X at the opponent selection screen in single duel mode. 

Alternate Backgrounds:
In the main menu highlight single or triple duel and press X. The background will change to an unlocked card.