Killer Instinct

Go to Single Player - Master - Practice - Aria - Any opponent
Now you want to pause the game by pushing then hit until you are at Practice Options. Now you want to go to Instinct Meter and change that setting to Infinite.

Now to quickly explain Aria. She has 3 different body mods in which she can change (Bass Body, Booster Body, Blade Body) which you can see up the top right of the screen. The way you switch body parts is by pushing & .

Now that we know how Aria works, we will now get the Achievement.

You will want to equip the Booster Body, then push up on the right stick and do the following combo for Crescendo:

You will want to equip the Blade Body, then push up on the right stick and do the following combo for Allegro:

You will want to equip the Bass Body, then push up on the right stick and do the following combo for Dissonance:

Once you have successfully enter the combos, the achievement will pop :)
NOTE: Make sure you hit your opponent, if they block it, it does not count.

You can earn this achievement in every game mode, but it will be easier to do it in practice, or in VS mode with a second gamepad.

In practice mode [Single Player -> Master -> Practice] you can set the Instinct Meter bar to be always full: pause the game and press two times. Here you can set the Instinct Meter to Infinite.

To earn the achievement go near your opponent, go into Instinct mode (+, or ), and (assuming you're attacking left to right) press:

Crescendo: ,,
Allegro: ,,
Dissonance: ,,

NOTE: Normally you should change body form to be able to perform every single move listed above, but it's not needed when you are in Instinct mode. In fact, for this achievement you have to avoid to change body form.
Just be sure to hit your opponent with each of the 3 moves, and do that while the Instinct Meter is still active.