Every character has an arsenal of special moves at their command that require simple directional taps followed by an attack button.
These are not the complex rolling motions of Street Fighter and other games: You’ll be tapping three directions at the very most, usually two. So long as you tap the buttons reasonably quickly, you shouldn’t have a problem.
The key special move motions are "back, forward", "down, forward", and "down, back." Even without looking at the game’s extensive move list, you should be able to figure out a trick or two easily.
Typical special moves
Most Injustice 2 characters have at least some weapon that fires a projectile at long range, and they’re very fast and powerful. Throwing projectiles at a distance is a very effective strategy against players too headstrong to stop charging in. Just make sure you aren’t too predictable about it.
Projectiles pass through other projectiles rather than nullifying each other as in other fighting games. So rather than having a "fireball fight," two players who throw projectiles at each other at once simply exchange shots.
Some characters have special throws that require a command to be input, hence the name. The big difference between these and regular throws is that, in exchange for being slightly slower, they cannot be broken. An uncommon move, but a few characters excel in this category. If you like landing throws you may want to check Swamp Thing or Bane out.
A few characters can teleport from one side of the screen to the other in something of a Pac-Man effect. This is really annoying the first time it happens, but after that it can start to get predictable. Players will play cautiously against a character with this ability, and there are usually big holes in their windup that can leave the teleporter wide open.
Rather than trying to lead with these moves, wait for a moment when the enemy won’t expect it.