Castlevania: Dawn Of Sorrow Codes -

Completion bonuses:
Successfully complete the game with the best ending to unlock the Boss Rush mode, Sound Test mode, and New Game+ options.

Successfully complete the game under the hard difficulty setting as Soma to get the Hell Flame Soul move.

Successfully complete the game with any ending to unlock Julius mode.

Rare Ring:
Have the Game Boy Advance game Castlevania: Aria Of Sorrow in the cartridge slot and start a new game to have the Rare Ring in your inventory.

Mina Doll:
Have the Game Boy Advance game Castlevania: Aria Of Sorrow in the cartridge slot. You will see a Mina doll in the background of Yoko's shop waving her arms. 

Potion:
Successfully complete Boss Rush mode.

Terror Bear:
Finish Boss Rush mode in less than eight minutes to get the "Terror Bear" weapon.

Nunchakus:
Finish Boss Rush mode in less than seven minutes to get the "Nunchakus" weapon.

Death Robe:
Finish Boss Rush mode in less than six minutes to get the "Death Robe". It a powerful armor, but Dracula's Tunic is better.

Rocket Launcher (RPG):
Finish Boss Rush mode in less than five minutes to get the Rocket Launcher "RPG".

Chaos Ring:
Get 100% of the Souls to get the Chaos Ring, in the abyss.

Worst ending:
Defeat Dario Bossi during the second battle.

Bad ending:
Use the Paranoia Soul to enter the mirror during the second battle with Dario Bossi. Defeat Aguni, then return to the other side of the mirror and get the Magic Seal. Then, go to the center of the castle and enter the Boss door without Mina's Talisman.

Best ending:
Use the Paranoia Soul to fight Aguni. Collect the Magic Seal then return to the center of the castle. Have Mina's Talisman equipped when you enter the Boss door, then complete the game.