Also, getting Ultima weapon is more difficult to obtain in Final Mix due to changes in material requirements and new heartless. I don't know the specifics ; Weaponknight / Seven Force or another more familiar can elaborate if they want.
The weapon itself is not that bad. You just need some new items from Final Mix and three Thunder Gems. The problem lies in making it available at the shop.
On the positive side, you have Encounter Up now, so it's easier to respawn waves of heartless.
Things to worry about:
Some of the new heartless are outright ridiculous, some of them really hard (if you think NeoShadows are the pushovers from KH2, think again), but some are comically easy.
You'll reach a point that will require about 30 (yes, thirty) Lucid Shards. Enjoy killing those cockroaches!
There are more items than the original game, and they require more items.
Orichalcum doesn't drop anymore. You'll have to buy it for 5000 munnies at the shop.
And at the end, you'll have made it for nothing, because Sephiroth will give you the One Winged Angel. Not to mention that #TeamStaff will be rocking the Diamond Dust a lot earlier.
I can confirm that giving Goofy or Donald items is useless. They waste it almost immediately lol. Only give them items for bosses
Goofy just used a mega potion when I got hit once by thunder to a Black Ballade
gooby pls
Goofy is preadjusted to use HP items as soon as you're hit. Did you customize his AI?