Beat the game and let the credits and ending sequence play through to the end. Save the game and play again with all Fusion Demons from your previous game.
The locations of all the Elemental gravestones to unlock the level 3 fusion monsters are as follows:
Darkness - In the room at the top of the tower in the Blue Castle where you have to fight Yuri - look for a glint on the floor
Light - In Roger Bacon's house - run right round past the vending machine.
Fire - In a chest in The Caglio Asylum.
Earth - Nina has it in Bistritz.
Air - Prague. Go talk to the barkeeper, then go and check out the toilet. Talk to the guy and give him tissues. When you try to leave the bar he'll give you the stone.
Water - Rouen, some guy in the street will give it to you when you talk to him.
Super Fusion Abilities
In order to unlock the super fusion powers of the level 3 Fusion Monsters the power called '????' for Forron, Sandalphon, Lobo, Egil, Seravi and Czernobog simply morph into them in battle and allow them to go Berserk, they will use the power and thus you will learn it. Simple.
Bonus Fusion Monsters
There are TWO extra Fusion monsters besides the six elemental ones encountered in the graveyard.
AMON: When in the Nemeton Monastery Dungeon make sure you visit the huge red cauldron before confronting Albert Simon. You should get a destruction stone which allows you to acquire the amon fusion soul after you beat him. YOU NEED THIS TO GET THE NEXT ONE.
SERAPHIC RADIANCE: very tricky. Get the book of rituals from Nemeton Monastery by visiting it with Alice and Zhuzhen in your party after the battle with Amon. Read it and go to the Ancient Temple south of Prague. Follow the torches in the order of the rainbow ROYGBIV - where blue is aqua and Indigo is blue for some reason. You will get an item. Now leave and read the Book again. go back into the temple and folow the torches in reverse order. Fight Seraphim - he is quite tough , guard against status attacks
Now swap the Erotic Book if you got it from Denuhai's tower with Roger Bacon for the Pulse Tract - read this - it will give you an alternative pattern of torches to follow - though cryptic.yellow, red, green, purple, blue, red, Aqua. This will allow you to get the rebirth stone. now go to the graveyard and head through the gate to the sunset and the tree. Check out the sun and try to leave. You'll have to fight the Seraphic radiance - win and you'll have it Also check behind the tree for Yuri's ultimate armour
Keith's ultimate weapon
After you get the earthstone from Nina in Blizrites return to Blizrites and go Nina's store she will say she has seen a golden light at Blue Castle. Go to Blue Castle were the coffins are. You will a golden bat,you'll find out that the bat is Keith's brother and have Keith fight him alone if you could beat him in 6 turns you get the demon sword Keith's strongest sword.
Yuri's ultimate weapon
Go to the place where Roger Bacon teleports you to then come back. He will say he is working on a new exsperiment and needs your help. You will start running and the judgement ring will appear. You will have to hit it ten times in a row but it gets faster and faster. If you get it right it will send Bacon to the moon. He will return to you and give you Yuri's ultimate weapon.