Pic and Gorc were, I believe the most challenging, since you have to battle their different fighting styles at the same time, except one time when I went through it Pic got stuck somewhere :-p so that made it a lil easier
It should have been hard. But I just attack Gorc first, then go for Pic. Too easy. But the hard battle when I first reached the last level was, well, difficult for me. I had no clue what to do when he meditated. I somehow thought the statues were supposed to reach the middle. Then, I kept losing for some odd reason...