In order to unlock this trophy, you use must Feral Link successfully 100 times total in battle.In order to use Feral Link in battle, you need to attack the enemy alongside your monster to have the feral gauge slowly fill up, once it's eventually full you will have the ability to press
to activate it, depending on what monster you have, it will either do a QTE or not. If it does do a QTE, you have to
SUCCEED the QTE for it to count,
if you miss a button then it will not count. I for one had a Medical Flan, so his Feral Link didn't require a QTE, it was a simple heal ability and it was fine.
So do Feral Link in battle successfully 100 times, and this trophy will easily be yours, easy trophy, it'll just take time to get is all.