Oh yeah Chaos is awesome on Monk. Holy, Protecga and Shellga? Yes please. I have 2 Monks, with Penelo being the other and also a Black Mage. Gave her Chaos and Zodiark. Basch I accidentally made Monk instead of Uhlan, so I figured I'd still give Penelo the Monk stuffI feel like Chaos makes far and away the best sense for your Monk.
Hashmal's a tricky one, since it gives some really high-quality White Magick to your Knight *or* your Monk.
Everyone's got loads of offensive options in this game but the more efficiently you can keep your HP/buffs up using your full party's MP pool the better.