Kingdom Hearts II Organization XIII Boss with the most Sporadic Pattern?

I was curious as to what people think on such a question.
I noticed a lot of the times that in KH2 (and, sadly, many more games), the bosses often are very predictable with their own pattern. I fight Saix and Xigbar a lot and I memorized their pattern after two tries.

So, which Organization XIII boss do you believe has the most random attack pattern?

I find it to be Xaldin, but that's just me.

I thought Sephiroth was unrealistically predictable.

 

I that, Xigbar and Xaldin. Just because I could not tell when, he was going to change the playing field