Unlike raid bonuses, Trials of Reckoning bonuses stack with each other, and bonus VCs need to be equipped.
Since you don't even need to bother with the enemy minions, it can be easier and faster to go full mono water team and focus on phoenix for a fast win.
If you are mainly going after points, then you'll want to use other units for the bonus stacking. Taking more turns can end up lowering your points, so if you never levelled up any of the unit bonuses but want to bring them to the party, lower their AGI so they get less turns.
It's worth mentioning that if Phoenix auto revives, the attack chain still continues. If you want to keep building up chains for higher points, then you can consider not removing Phoenix's Reraise.
Ildyra for LB and water damage.
Glaciela has multiple hit attacks for high water chains.
Tidus has Hastega and CT reducing attacks, also LB for multi hit attacks.
Viktora (Winter) can remove buffs to get rid of Phoenix's Reraise.
Moore for the XL points bonus.
There are other units that can remove debuff or the Reraise if you want an auto-able grind. Only Corwell is part of the unit bonus, and he gets his dispel move from Sniper main job.