Kingdom Hearts Final Mix

For this trophy you must defeat Unknown, who is located in a dark portal in the Chapel. When you enter the portal you will meet Unknown and initiate the boss fight. Defeating Unknown is very possible on Beginner at around Lv.65-70.

At the start of the fight, summon Tinkerbell immediately and cast Aeroga on yourself. Unknown uses a variety of projectiles and will move around the screen a lot. When you finally get close to him he will use a Mirror Wall to protect him and then go through it to attack you when you are stunned from the wall.

If you are at a high enough level you could just attack him continuously disregarding all his attacks and you should be able to finish the fight miraculously easy.

He Who Doesn't Exist