I decoded Marluxia's moves and attacks after a while because I knew that the final boss was of course going to be difficult. Marluxia showed no true problems for me.
The second fight with Ansem took me two tries to get him, but it wasn't all that difficult.
Larxene was a joke for me. I'm sorry, but I guess because I was expecting difficulty, I got through it easier because I was well prepared.
Axel was no real threat for me.
Repliku four...now that was something. The first three encounters were fairly easy, in truth. But, that battle was brutal! It took me four tries to get him.
Vexen...OMG. I took Vexen for granted because of the picture I painted for him. The first encounter was pretty easy...but I don't know how many times I had to fight Vexen in Twilight Town to get him.
Geez, this is kinda embarrassing, but Vexen was the most difficult for me.
I despised his battle quotes too. He sounded like Fruity Pierre! (Well, that doesn't mean it didn't fit him well.)
:x