Ayane: Easy C3 through C7; Normal C8 through C15; Hard C15 through C20.
Bass: Easy C3 and C4; Normal C5 through C8.
Bayman: Easy C3 and C4; Normal C5 and C6.
Gen Fu: Easy C3 and C4; , Normal C5 through C8.
Hayabusa: Easy C3 and C4; Normal C5 through C9.
Helena: Easy C3 through C7; Normal C8 through C11; Hard C11 through C13.
Hitomi: Easy C3 through C7; Normal C8 through C11; Hard C12 through C14.
Jann Lee: Easy C3 and C4; Normal C5 through C8.
Kasumi: Easy C3 through C7; Normal C8 through C15; Hard C15 through C20.
Lei Fang: Easy C3 through C7; Normal C8 through C15; Hard C15 through C20.
Leon: Easy C3 and C4; Normal C5 through C8.
Tengu: Easy C3.
Tina: Easy C3 through C7, Normal C8 through C14; , Hard C15 and C16.
Zack: Easy C3 and C4; Normal C5 through C8.

Note: Some costumes can be unlocked by completing story mode repeatedly with the same character, without changing the difficulty setting. For example, Tina has a total of 14 costumes that can be unlocked by completing the game each time with her to get a new one.

Note: You can also unlock costumes through time attack mode, which you need to use anyway for Tengu, Bayman, and Hitomi. Change the difficulty if the game stops unlocking new costumes. Any girl that has fifteen or more costumes must be set to the hard difficulty setting.

More bouncing:-  Set your age to a higher value, such as "99" in the options to increase the amount of bounce the girls have.

Fight as Bayman:-  Accumulate a total of ten hours of game time. Alternately, successfully complete story mode as Leon under the normal or higher difficulty setting.

Fight as Hitomi:-  Successfully complete story mode with Ein with a saved game from Dead Or Alive 3 or Dead Or Alive Xtreme Beach Volleyball on the hard drive.

Fight as Raidou (Dead Or Alive Ultimate Disc):-  Complete the game with all eight characters to unlock Raidou.

Fight as Tengu:-  Successfully complete story mode with all characters.

Alternate stages:-  Press Black or X when making a choice at the stage selection screen. Note: Not all stages have alternate versions.

Alternate hair:-  Press X, Y, White or Black when making a choice at the character selection screen. Note: Not all characters have more than one hair style.

Collection mode:-  Enter survival mode for the first time, and pick up items as you defeat them. When you die, collection mode will be unlocked. From now on, any time you pick up items in survival mode they will be viewable in collection mode from the main menu.
Information in this section was contributed by Big Mike.

CG Gallery:-  Unlock all alternate costumes to get the CG Gallery option.

Dead Or Alive 3 Booster Disc:-  Unlock all alternate costumes. This saves a file on your Xbox that will unlock costumes in Dead Or Alive 3, just like the actual booster disc for the game.

Dead Or Alive "Icons" episode:-  Unlock all alternate costumes.

Player announcements:-  Successfully complete the exercise sessions in sparring mode as Kasumi, Ayane, or Tengu to unlock new announcement voices for that character.

Control victory view:-  During the ending victory sequence, press L or R to rotate the view. Use the Right Analog-stick to move the view up or down.

Ayane: Hidden FMV sequence (Dead Or Alive 2 Ultimate Disc):-  This can only be done in Ayane's story mode. When you get to the fight with Kasumi and the snow level (it will always be the snow level when you fight Kasumi), knock/get knocked down into the lower level, the ice cave, and continue fighting there. Win the round with a final blow that will send Kasumi a considerable distance from you (about fifteen feet away from Ayane, QCF + Kick works well). Instead of the usual intermission sequence, Ayane will perform a magic technique and shoot some sort of fireball at the unsuspecting Kasumi.