In this video guide I will show you how to perform two different fatalities with Scorpion. For the first 10 characters I just used the klassic towers to get the achievement progress for I Want It All. Make sure to put it on very easy to make things quicker. Also pick the shortest tower.
After getting your I Want It All achievement the method with be a lot faster. Once in the main menus press the start button to go into the options menu. Scroll down to change the rounds to win to one. Then back out, go into the fight menu, select local, make sure to press X to turn on the CPU, and then select your character. You only have the one health bar to deal with to get to the fatality.
Achievement progress also counts if AI do a fatality.
You're Next (Far) - Back, Down, Down, X
Chain Reaction (Far) - Down, Forward, Back, Y