All we could do for the moment is speculate on what the "iconic" characters in each franchise will be. Although I am not too familiar with most of the DC universe outside of Batman I can't list any more characters than who are on the Justice Leauge. I'm sticking to what I do know however, and that is Mortal Kombat. With the exeption of Sub-Zero and Scorpion, the following characters I feel would best represent Mortal Kombat as a franchise for this cross-over game.

Raiden - Many people outside of the hardcore fans of Mortal Kombat would recognize Raiden as "the guy with the hat that shoots lighting" Raiden is just as iconic as both Sub-Zero and Scorpion are and my guess would be that he would be the head of the Mortal Kombat characters just like how Superman would be for DC.

Reptile - Outside of Sub-Zero and Scorpion I believe that Reptile is the most recognized and one of the most popular Mortal Kombat characters to date, it would seem strange if he were not a playable character in this game.

Goro - Knowing DC, there are going to be some huge bulky types on their roster. Goro is the most notorious of this type of fighter and is a huge icon for Mortal Kombat, who would think that an ugly 4 armed monster would be a poster boy for something?

Shang Tsung - He is arguably the most evil character in Mortal Kombat, and was the original boss character. Most fans would agree with me that he deserves a spot on this roster. Shang Tsung was a very unique character in the 2-D games. If the team developing the game is peeking their heads at this do us fans a favor and include his morph ability again?

Kung Lao - A kick-ass Shaolin Monk with the ability to throw a razor sharp hat. Kung Lao was so mysterious yet so cool in MK2 in his first apperance and played awsome in the 2D games. His hat alone is iconic in Mortal Kombat, he was a lead protagonist in the Shaolin Monks game so I think he has a fitting position on this roster.

Jax - The reason that Jax deserves to be in this game is that most generic gamers who have ever played a Mortal Kombat game can remember Jax because of his metal arms and his comments such as "GOTCHA!" he adds more flavor and personality to the Mortal Kombat roster.

Kitana - I feel that out of all the female characters in Mortal Kombat it was tough, but I feel that Kitana beats out Sonya for the spot she deserves. The reason why I didn't put Sonya up is because Kitana is arguably more recognized by fans outside of the MK universe with her unique style. Kitana is a sexy assasin that uses fans with blades attatched to assault her opponents. Who would want to see a match-up between her and Catwoman? It just seems more fitting to include Kitana in.

Quan Chi - Since MK4 he has been stirring hell up, he has a really cool concept and is black to the core. Quan Chi was the poster boy for MK4 and has made a huge impact on the games since his appearance it would be a shame not to have him in.

Shao Kahn - Most intimidating boss who smashes you with a hammer while at the same time talks shit to you. Need I say more?

Liu Kang - Liu Kang is like Ryu to Street Fighter, Mario to Smash Bros., Kilik to Soul Calibur ect. (you get the point) he's the hero of Mortal Kombat and his death in Deadly Alliance shook the story down to its very core. I guarantee he will be in this game.