What I've tried is:

• Kaiser/Exorcist with Auto Undo, Undo Trois and Dawn of Odyssey. Basically, it oneshots most early bosses with Blinding Light, and works as a backup healer against Diamante and some other bosses which can deal massive damage party-wide.

• Guardian/Dark Knight with Soul Boost, Adversity, Dual Wield and Katana Lore: main physical damager. Consists in spamming Rage, then Minus Strike (with more than 15k HP it's max damage), alternating with Soul Cannon every so often (which also deals max damage). Rage works better with a Sloth.

• Astrologian/Bishop with Spellcraft, Mp 20% up, Limit Breaker and Prolong Support. The healer (Bendiction blast works wonders). This setup is mainly for Diamante, but I don't know what could change on this to make it a viable DPS without booking heals. I'm thinking Diabolism for Astrologian...

• Yokai/Time Mage with Spellcraft, Time Slip, M. Atk 20% up and Steady MP recover. This one will suffer some changes, because the MP recover isn't that important with 2k MP, for example. This job setup allows for Meteor Blast (which, based on my testing, works better than Meteor Rain) spam with Echo. So it can get really crazy with 8 Echo procs in a row, or do just one, and it deals max damage every time, so do make your calculations.

Anyway, that's how I do it. Everything dies in one turn except bosses after Diamante (and Diamante, but Diamante is a pain anyway, and is the only reason I run exorcist and astrologian). I'll go around trying all that has been said.