I feel like I'm doing something wrong against ELT Fina.
Agrias
DKC
Chizuru
Cecil
Refia
All maxed levels/rarities
My equipment isn't super awful, but I don't have any TMs other than DKC having Barrage (I haven't been farming anyone else's since I got that last week). Even taking a 700-800 ATK Noctis with me I can barely get her to 50% before the pain comes. The status hits are the freaking worst part, so I flipped things around a few different ways to try mitigating it or just blasting past the threshold to kill her, but I'm not doing enough damage for that, now.
Also, I REALLY wish the damned thing wouldn't crash, nuking my NRG at the same time. I understand not continuing but taking my NRG, going in and the game crashing when it tried to load the first battle is rat's ass.
The equipment doesnt care much, its the mitigation and ailments prevention that are needed here.
I see that you talk about using a noctis.
First advice: Fina at 50% HP cast meteor and at 30% HP she cast ultima. If you pass the 50% and 30% mark in only one stroke (that would probably happens with the noctis) fina will cast meteor AND ultima in the same turn. That is instant death, so try to damage her and she uses meteor one turn and ultima the other turn so you can heal and survive.
Advice 2: Chizuru is too glasscanon for this trial. Unless you have her full potted and with HP equipment (muscle belt and HP materias) she can endure the trial but would lose much power and she would not be effective in this trial.
The same thing with Agrias (yes, ingus is more weak than agrias, but he offers more versatility to the fight, and hes worth the gamble)
Advice 3: Equip Cecil a Jewelled Ring (inmune to palsy and stone) and cast provoke. Fina will likely attack cecil and her attack that gives confusion, palsy or stone, cecil will prevent 2 of 3, and you will not have to worry about that.
You should see my 2 videos i made with the battle with fina with no tms and no base 5 star units. You with a noctis 800 ATK should be able to obliterate her.