Which forms did you find the hardest, it seems to be different for everyone.
I originally found fighting the 3rd form the hardest,
I was playing it slow, cause i had my limit gauge almost completely out, and anyways i was on the last bar after 10 minutes of playing it slow when... SHE HEALED HERSELF!! Up full then she killed me,
I was like NOOOOOOOOO!
Only to find i restarted that fight with full limit gauge and full health so i just shruged and used limit 3 times and she was dead in a minute
I have to say I found final form the easiest to fight...
Maybe im weird like that...