Variations are a new game mechanic that debuted by NetherRealm Studios.
Each character has three different variations a player can choose from after selecting a character. Variations can include a unique set of attacks, special moves, or weapons that are only exclusive to that variation. Some Brutalities are also exclusive to certain variations as a character must be capable of performing move to enact the finisher.
Though variations play a key element to the character's abilities and attributes, it is entirely optional to play without one. To do so, simply hit Up twice and then press Y/Triangle, depending on your system.