So, I put in the NPC codes and P1 modifier codes here:
_G Mortal Kombat Unchained [US]
_C0 Player One always SCORPION
_L 0x00592A00 0x00000000
_C0 Player One always BARAKA
_L 0x00592A00 0x00000001
_C0 Player One always NOOB
_L 0x00592A00 0x00000002
_C0 Player One always SUB ZERO
_L 0x00592A00 0x00000003
_C0 Player One always MILEENA
_L 0x00592A00 0x00000004
_C0 Player One always NIGHTWOLF
_L 0x00592A00 0x00000005
_C0 Player One always ERMAC
_L 0x00592A00 0x00000006
_C0 Player One always ASHRAH
_L 0x00592A00 0x00000007
_C0 Player One always SINDEL
_L 0x00592A00 0x00000008
_C0 Player One always LI MEI
_L 0x00592A00 0x00000009
_C0 Player One always BO'RAI CHO
_L 0x00592A00 0x0000000A
_C0 Player One always HOTARU
_L 0x00592A00 0x0000000B
_C0 Player One always KENSHI
_L 0x00592A00 0x0000000C
_C0 Player One always SMOKE
_L 0x00592A00 0x0000000D
_C0 Player One always HAVIK
_L 0x00592A00 0x0000000E
_C0 Player One always TANYA
_L 0x00592A00 0x0000000F
_C0 Player One always LIU KANG
_L 0x00592A00 0x00000010
_C0 Player One always LIU KANG GHOST
_L 0x00592A00 0x00000011
_C0 Player One always KIRA
_L 0x00592A00 0x00000012
_C0 Player One always KABAL
_L 0x00592A00 0x00000013
_C0 Player One always KOBRA
_L 0x00592A00 0x00000014
_C0 Player One always JADE
_L 0x00592A00 0x00000015
_C0 Player One always DAIROU
_L 0x00592A00 0x00000016
_C0 Player One always RAIDEN
_L 0x00592A00 0x00000017
_C0 Player One always DARRIUS
_L 0x00592A00 0x00000018
_C0 Player One always SHUJINKO
_L 0x00592A00 0x00000019
_C0 Player One always SHUJINKO 13
_L 0x00592A00 0x0000001A
_C0 Player One always NOOB & SMOKE
_L 0x00592A00 0x0000001B
_C0 Player One always MONSTER
_L 0x00592A00 0x0000001C
_C0 Player One always ONAGA
_L 0x00592A00 0x0000001D
_C0 Player One always GORO
_L 0x00592A00 0x0000001E
_C0 Player One always SHAO KAHN
_L 0x00592A00 0x0000001F
_C0 Player One always FROST
_L 0x00592A00 0x00000020
_C0 Player One always KITANA
_L 0x00592A00 0x00000021
_C0 Player One always JAX
_L 0x00592A00 0x00000022
_C0 Player One always BLAZE
_L 0x00592A00 0x00000023
_C0 Player One always RANDOM
_L 0x00592A00 0x00000024
_C0 Player One always mkda JAX
_L 0x00592A00 0x00000025
_C0 Player One always mkda RAIDEN
_L 0x00592A00 0x00000026
_C0 Player One always mkda QUAN CHI
_L 0x00592A00 0x00000027
_C0 Player One always mkda KUNG LAO
_L 0x00592A00 0x00000028
_C0 Player One always mkda JOHNNY CAGE
_L 0x00592A00 0x00000029
_C0 Player One always mkda SONYA
_L 0x00592A00 0x0000002A
_C0 Player One always mkda NITARA
_L 0x00592A00 0x0000002B
_C0 Player One always mkda SHANG TSUNG
_L 0x00592A00 0x0000002C
_C0 Player One always mkda FROST
_L 0x00592A00 0x0000002D
_C0 Player One always mkda KITANA
_L 0x00592A00 0x0000002E
_C0 Player One always mkda DRAHMIN
_L 0x00592A00 0x0000002F
_C0 Player One always mkda BLAZE
_L 0x00592A00 0x00000030
_C0 Player Two always SCORPION
_L 0x00592A6C 0x00000000

And they don't show up in the standard cheat menu, can anyone tell me how to activate them?

first, these are cheats for "cwcheat device" , don't know if they work on npc.

further you have to enter a cheat at database like that:

_S ULUS-10102
_G Mortal Kombat Unchained [US]
_C0 Player One always SCORPION
_L 0x00592A00 0x00000000
_C0 Player One always BARAKA
_L 0x00592A00 0x00000001
.
.
.
.

@Admins: Could some one explain why not answer to threads older than three months!?!

Thanks, for helping me, I'll answer your question. You simply can't reply to threads older than 3 months because that's when they're considered dead. Bumping them after that is considered spamming the boards with dead topics.

Yup, Vash is basically right. Once a thread is dead though, another user can re-make it if they really want to discuss the topic that badly. Also, that 3-month-bump rule does not apply to Fan Submissions (actual submissions, not posts) and varies based on the forum you're in (some forums have threads older than 3 months still on the first page, like this one).