Hi, I would love to help you but discussion of emulators and roms are not allowed here. Sorry. Go to the stickied threads on the top for the Koffins Guide/cheats for GBA versions of MKDA and MKTE for unlocking the characters.

But he didn't ask for emulators or roms, just codes, which AFAIK aren't illegal. So here's the code for unlocking bonus characters in MKTE:

030021e8:0?

Substitute ? with the signs below to play as any of the unlockable characters:

9 - Hsu Hao
a - Reptile
c - Drahmin
d - Noob Saibot
e - Sektor

Sorry, never knew that.

Where exaclty do i input them ?
In VBA i can :
Add cheat (adress,value ,description to fill in)
Add Gameshark (description,code)
Add Codebreaker (description,code)

There are 'Code', 'Cheat', 'Gameshark' and 'CodeBreaker' buttons in 'Cheat list' menu. And you should choose the first one and enter the code there. Description is not necessary, but you can enter the name of the character depending on code. Then you can add it to the list and enable/disable it at any time.

Ok they worked but only one at a time and only that character was playable.
For example i input the code for Hsu Hao and only him was selectable from the entire screen.
I would like to unlock all of them at once and make every character selectable.
I remeber having succes with gameshark or codebeaker but can't remeber exactly which if it was MKTE or MKDA and what version of VBA i was using .
I noticed there are different versions of Gameshark and Codebreaker and they are not backwards compatible.
Maybe VBA 1.8.0 beta 3 uses some new codes and i only found old ones that don't work .I will try an older VBA to see if i'm correct.
Anyway,thanks for all your support.

I finally did it .It wasn't a matter of VBA version but i had to create a profile in the game ,so that the codes would work .In conclusion ,the codes found on gameshark.com and codebreaker.com ,they work of course .

I have MKTE for VBA and i can only get those character codes to work.

You need to create a profile ,otherwise gameshark and codebreaker codes won't work .At least for unlocking all the fighters.

i did create a profile. whenever I try to put the codes i found on gameshark.com, it says error, code format is xxxxxxxxyyyyyyy or some thing like that.

I know this may sound stupid, but be sure to enter them in Add->Gameshark and not Add->Code .Also make sure you get the codes for your region E or U.There's no reson why it won't work.

I have the U version of the game and I press Input Gameshark Code, I put the code in, and it doesn't work.