The Strongest Creature Trophy in One Piece: Pirate Warriors 4

You will definitely achieve this if you are going for the Platinum. Warriors/Musou games are all about clearing large amounts of enemies with attacks. Simply play the game and you will earn this naturally. I earned this after the Dramatic Log while going through the Treasure Log. If you are curious, your enemies defeated counter can be viewed on any Battle preparation screen by going to Player Information and selecting Results.