I know, I know. It's not going to happen in this game (maybe next game?), but it's still fun to come up with a few creative ones.

If it were to happen, I doubt they'd have a unique tag-team finisher for EVERY combination of fighters possible (there'd be hundreds), but I could see it happening for a few specific pairings.

Here are some ideas:

Icy Hot [Sub-Zero and Scorpion]
Sub-Zero freezes the opponent in place. Scorpion summons fire around the encased victim. Sub-Zero keeps the opponent frozen with a continuing ice beam while the intensity of Scorpion's flames burn the opponent's flesh off, still under the ice. The body dissolves until all that is left is a skeleton entrapped in ice.

Acid Rain [Rain and Reptile]
Rain starts up a thunderstorm. As it rains down on the opponent, Reptile somehow infuses the dropping water with his body's natural acid. The resulting raindrops burn and singe the opponent's body until they fall dead.

Portal Kombat [Noob Saibot and Scorpion]
Seeing as how Noob's portals are blue and Scorpion's are orange, they are perfectly fit for a reference to Valve's Portal game (which was also released on April 19, coincidentally enough). Anyhow, Noob opens up a portal on the ground, while Scorpion starts one up on the ceiling/in the air. Noob holds the opponent upside down from the legs and dips them into his portal, so that the victim's head is popping out from Scorpion's at the top. Both Noob and Scorpion simultaneously close their portals, so the victim is ripped in two. Noob holds the lower half of the body from the legs as Scorpion catches the severed head and proudly displays it.

Any ideas from you guys?