If you want to unlock ALL the hidden Characters, Artwork and Endings so everything is unlocked in the game you have to complete ALL 40 missions which is easier said than done.

To unlock the Special Ending pictures for the Ending gallery beat the game using the corresponding teams.

Unlock King of Fighters Main Characters Team:
Kyo, Ash, K'

Unlock 2003 Main Characters Team:
Duo Lon, Shen, Ash

Unlock Elder Brothers Team:
Adel, Ryo, Gato

Unlock Elder Sisters Team:
Vanessa, Elizabeth, King

Unlock Kyokugenryu:
Yuri, Team Ryo, Robert

Unlock Authority Team:
B.Jenet, Elizabeth, Whip

Unlock Bird Team:
Duck, Griffon, Jazu

Unlock Buriki Team:
Gai, Ryo, Silver

Unlock Girls Team:
Athena, Momoko, Kula

Unlock Justice Team:
Athena, Kim, Griffon

Unlock Ninja Team:
Eiji, Mai, Jazu

Unlock One Sided Love:
Kensou, Ramon, Team Robert

Unlock Adel's Ending:
Adel and anyone else

Unlock Reinventing Oneself:
Kim and anyone else

Unlockable Characters
Complete the following tasks to unlock the corresponding character

Unlock Gai:
When he challenges you defeat him in Arcade mode

Unlock Sho:
When he challenges you defeat him in Arcade mode

Unlock Adelheid :
When he challenges you defeat him in Arcade mode

Unlock Jyazu:
When he challenges you defeat him in Arcade mode

Unlock Silber:
When he challenges you defeat him in Arcade mode

Unlock Shion:
Defeat her in Arcade mode (the fight befoer Magaki)

Unlock Shion - Alternate method:
Complete Challenge number 5

Unlock Magaki:
Complete Challenge number 6

Unlock Robert Garcia:
Complete Challenge number 10

Unlock Mai Shiranui:
Complete Challenge number 20

Unlock Tung Fu Rue:
Complete Challenge number 25

Unlock Hotaru Futaba:
Complete Challenge number 15

Unlock Ex Kyo Kusanagi:
Complete Challenge number 30

Unlock Mr. Big:
Complete Challenge number 35

Unlock Geese Howard:
Complete Challenge number 40

Unlock Geese Howard - Alternate method:
Fail the mission over 20 times and pause in the middle of the match and then quit


Select Secret Character as Opponent in Stage 4.
When you reach stage 4 in Arcade mode a secret character will challenge you depending on how many LDM you have landed

To fight Gai:
Land at least 1 LDM

To fight Sho Hayate:
Land at least 3 LDM without any character dying

To fight Jyazu:
Land at least 6 LDM without any character dying

TO fight Silber:
Land at least 6 LDM without any character dying

To fight Adelheid:
Fail any of the requirements


Unlock ALL Secret Characters.
Successfully complete ALL the challenges in Challenge mode.