There's a trick to it, even to Chaos mode against the one on ones.
With Hubert, fighting him long range is foolish, since they come out so fast (even ones that have cast times) and your healing is almost non existent. Luckily it's easy to interrupt his regular attacks (especially with drawing your sword with O), and Infernal Torrentx2 into sheathing worked for me.
Malik, you HAVE to evade spectral chains (goddamit Malik why don't you near-instacast when you're on MY team?), else you're gibbed even if you block it. Luckily, side evade makes you nigh invulerable to it, but if you don't have CC, you're done for. Apart from that, he was like hubert. A bit easier I suppose (although admittedly more unforgiving), since this time I have enough CC to Infernal Torrent X2 into Void Sword, which auto-sheathes your weapon and does nice damage to boot.
Besides, you're supposed to lose once, as you get another skit for the rematch. XD
Now what I'm having problems is Master mode in the Arena. You have to beat the mask man ONE ON ONE? (regular mode you get your entire team) Where Mystic Artes are sure fire death in Chaos mode without All Divide (which you don't have access to in the arena)? Yeah, I'm stumped...
But goddamn Emeraude. Ever since I 'discovered' the half stat spellbooks (I didn't look at my spellbook list for a long time), I've been trying to beat bosses with them. Even with All Divide and the "50% damage reduction if damage is over 750 (500 with Cheria)", her Mystic Arte gibbed my party. Then again I guess I shoulda used more people in B mode... them all using relatively short attacks, I guess I was just ASKING for her to use it on me.
Will try again tomorrow. I know she's easy enough without the spellbook in Chaos mode (didn't even need All Divide), but I LOVE challenges.