I may need to call in some advice for this one then, Highest Characters are Cloud, Vincent and Yuffie at levels 51,51 and 53 respectively. Everyone else is around the mid 40s. As for Defence I'm mostly covered as I think several of his attacks use the Shoot element and Protect Vests can halve that.
However I'm struggling to put out a reasonable amount of damage. I would have liked to use Neo Bahamut=Added Effect on my Weapon to inflict Dual status but I'm not sure it works. Also not sure if Keelhaul Armour is Immune to Dual or not (Probably is), so I doubt using the Summon itself would inflict it either.
This fight is almost making me wanna go back to stopping the runaway train heading for North Corel.
I guess it'll become tricky from there at rank 0 because of bosses having way more health (so longer fights). Having Vincent doesn't help because of his limits being pointless against bosses. If you still want to play with him, then he will obviously be your MAG nuker having the highest one at rank 0.
A quick setup would be (only mentioning what is mandatory) :
- Cloud : Command Counter = Deathblow (could be on Yuffie as she should have a higher %atk), Counter Attack, Elemental = Ramuh (in weapon), Cover, FullCure (you don't need MAG, it costs lot of MP but Cloud won't use any other magics)
- Yuffie : Restore = All, Barrier = All, Haste =All, Elemental=Leviathan, Counter Attack (if you have more than one), Enemy-Skill (Aqualung will deal water damage)
- Vicent : Lightning, Heal (Osmose to keep up MP), a ton of magic materias to boost his MAG stat
I really doubt you have Steal lvl 2 (Mug), so linking it with added cut would be pointless. Linking deathblow with added cut is not recommanded with your team because of Cloud having a not so high accuracy, and Yuffie will be healing more than using Deathblow.
Equipments :
All three should have a crystal bangle to get 6 materias slots linked and str/mag. Cloud need a STR/DEX accessory (Fire ring is really good, it will also absorb the topaz laser). Yuffie need a hybrid STR/MAG accessory while Vincent need a MAG one (earring ?).
As mentioned above, Topaz Laser will hit for fire damage, I'm unsure for the other lasers, so if you struggle in the last phase, remove crystal bangles and get some nullifying armors.
I'm checking if I forgot some materias, I'll edit.
Edit : You might want to link Lightning = Turbo MP to boost damage. You should have a Bolt 3 at this point, and enough gils to get ethers. (Quick reminder, Turbo Ether gives you back all your MP, cost 100 GP each [10 000 Gils at Gold Saucer]). Also I can't remember if I had 3 or 4 Counter Attack materias (Thanks to Cid weapon doubling AP), so basically 1st on Cloud, 2nd on Yuffie, all others on Cloud.
Edit 2 : I have no idea about the Dual status. It can't be poisoned for sure, slow didn't work when I tried (I only tried once, might have been unlucky).
I had the feeling the fight was globally easier than in 1.35 but way more longer, which seems a nice balance.