Animalities can only be preformed in UMK3
To preform an Animality you must first meet two criteria:
1. Both you and your opponent must have each won one round (It must be Round 3)
2. when you defeat your opponent on Round 3, you must preform a Mercy( Hold Run and press Down,Down,Down, and then release the Run button as any character) and then defeat them again after they have regained their health.
Once you've defeated your opponent for the second time, then you may get into range and enter the Animality combination to earn this trophy.
You can look up the combination for your current character in the Movelist in the pause menu.