Heres how you unlock the "hidden" characters:
PLAY AS KITANA: Defeat Arcade mode one time.
PLAY AS SUB-ZERO: Defeat Arcade mode two times.
PLAY AS KANO: Defeat Arcade mode three times.
PLAY AS QUAN CHI: Buy Koffin AI (4500 Koins) in the Krypt.
PLAY AS SHANG TSUNG: Buy Koffin FF (7500 Koins) in the Krypt.

The characters: Raiden, Reptile, Cyrax, Johnny Cage, Mavado, Drahmin, Bo Rai Cho, Hsu Hao, and Nitara, were not in the GBA version of MKDA. All of those characters are in the Mortal Kombat Tournament Edition (for GBA) though. They aren't in the MKDA/GBA version, simply because of memory. They couldn't fit all the characters. Most of the characters tho from MKDA/GBA arn't in MKTE/GBA.

to change the difficulty setting... go to options, then advanced, and 'CPU Difficulty' is at the top. You can change it from Very Easy all the way to Very hard.

if you need more help or explanation of the game, check out my website (It's in my signature)... or ask your questions here and I'll probably answer them.

There IS a multiplayer mode...right?

needleskane Wrote: There IS a multiplayer mode...right?

yes...via link cable.

death

First of all they cut out characters,to unlock Shang Tsung & Quan Chi you must by them in the Krypt and as for the rest: Kitana beat game one Sub Zero beat game twice Kano beat game on easy. To get money to buy stuff in Krypt beat people on arcade or survival, can buy alternate costumes in Krypt(change in costume color) to can costume highlight character and press R