What are the items needed for the ultima weapon in kingdom hearts

First, you need the ultimate recipe which is located at the twilight town mansion (you need to be there as Sora ) near the end of the game, it is located in the room with Donald and goofy's pods in it.

You also need to be a moogle lvl 9 so you can lessen S rank materials by half

There are seven Orichalcum+ items in the game

Seven Orichalcum+
1. Clear Atlantica.
2. Clear 100 Acre Wood.
3. Find the chest in The World that Never Was at the Brink of Despair after the big chest, don't go on the bridge but instead go left on a narrow path that leads to the chest.
4. Clear Goddess of Fate Cup in the Underworld Coliseum.
5. Chest in Twilight Town, in Sunset Terrace where you went earlier in the game for the Seven Wonders. Jump on top of the train and you will see a chest on the roof of the big building (the one closest to to the sunset station).
6. Chest in Space Paranoids during the second visit there, just before you fight Commander Sark and the MCP.

7. Collect every single material in the game and give it to the Synthesis Moogle. He will give you an Orichalcum+. You need every single material (shards, stones, gems, and crystals, including a regular Orichalcum).

You also need an energy crystal to lessen the amount of materials by half.

Energy crystals can be obtained from Bookmasters. Bookmasters first appear at the Radiant Garden. After the World that Never Was is revealed, Bookmasters may also be found in Space Paranoids. (they have green hats and obviously have books and float around)

The mythril crystal is found in certain chests or you can synchronize them.

You can obtain Dense crystals in The World that Never Was when you fight a Berserker nobody in Naught's Skyway. (the big nobodies with hammers)

You can obtain Twilight Crystals in the world that never was in ruin and creation's passage from sorcerers (the cube nobodies).

You can obtain Serenity Crystals from Assassins, Berserker, Samurai, and Sorcerers.
Assassins can be found in The World that Never Was in The Hall of Empty Melodies.Samurai are found in The World that Never Was in Naught's Skyway and Naught's Approach.

I recommend for you to have your party equip anything with lucky lucky like the Genji Shield or the meteor staff and if you have it the lucky ring. You can get the Shield by clearing the Titan Cup Tournament. You can get the Meteor Staff in Port Royal at the Ship Graveyard in a chest.

You can get Orichalcum from Bulky Vendors (rare heartless), or in chests.You should have at least one by now already.