DFFOO [JP][Kuja IW] Triggering the bosses counters you so you can counter them
Surprisingly, Kuja's IW is more about AOE dmg than holy enchanting (or dark enchanting for DKC's sake). This way is a little bit more management and risk, but as long as you are careful enough it should be okay. I may do an 100% AOE version for this.
Boss: Kraken x2
Both bosses have innate full attack type resistance (melee/range/magic)
Force Mechanics:
0%: 70% non-elemental BRV reduction
FA: Waterga+/++ (Break recovery, AOE magic BRV+HP)
It also grants DEF up to both bosses.
++version is only triggered if there is not one party member with a special buff at or above 4 stacks. It doesn't kill you though, it just grants the boss with additional BRV/HP dmg reduction buffs.
FT: 10T
Cannot be defeated during FT.
Weakness: (cancel FT)
FA that deals holy BRV dmg
Normal behaviour, gimmick and thresholds:
The boss usually goes on a two move cycle:
Slow blast (ST BRV) --- AOE Water (BRV+HP)
They will use a ST HP attack if you let them have too much BRV.
Slow blast would ... well put a SPD down on your character.
AOE water puts on an ATK up for them.
The gimmick of this fight is a permanent effect:
Arise: If one boss is defeated while one is alive, it will respawn at full health.
This gimmick is basically there because everything Kuja does are AOE.
Thresholds:
80-90/40-70/0-30%: Tentacle unleashed (off-turn)
Whenever they reach the upper threshold, all player characters get a framed SPD down and the boss that activates it would get an ATK up and 50% BRV dmg reduction.
On top of that, any elemental attack that is NOT holy or dark would get countered by black mist, a ST magic BRV attack that inflicts "darkness".
Tentacle unleashed state would be dispelled when their HP have reached the lower threshold.
Note that there is no dispelling it until they die after the last set is triggered at 30%.
General approach and rationale:
My team comp is formed mostly based on the tentacle unleash state countering any elemental BRV attacks other than holy and dark.
Since the boss themselves resist all attack types and the 0% FG dictates that all non-elemental BRV dmg gets a 70% reduction, it naturally points towards enchanting and imperilling the bosses (note that they are not naturally weak to any elements).
From there you can have two ways to go: either use holy/dark only attacks or go with having some other elements. Though that black mist counter move is merely a ST BRV attack, do remember it comes with a "darkness" debuff.
I chose to go with Ashe LDCA because the lightning/holy would trigger their counters. With Gladio LD/Machina LD/Yang LD counters/off-turn triggers being AOE (either split or 100% AOE), it is much easier to deal with the gimmick of this fight by keeping their HP evenly reduced.
These three are all melee attackers, so they both contribute to and enjoy Machina FR's HP bonus and HP dmg cap up.
In this particular case, on boss turns, AOE water would put SPD down on Yang and Machina, so we can stall a bit longer and fish for more counters. It would also trigger all three of them to hit the boss back, so there are a lot of extra HP bonus % for Machina's FR to be had.
Any boss counter would trigger Gladio/Yang to hit them back. The ST "darkness" debuff would be a non-issue since Gladio is impervious to debuffs. Off-turn events like "tentacle unleashed" would make Yang proc his normal counter because he doesn't like bosses doing things
The main concern with this method would be Machina's normal counter and HP+, which are some of the ST attacks that may lead to an accidental revival of a boss if one is to die before another. Those extra dmg are mostly offset by Gladio's EX/S2 +Yang's S1 when the HP% is higher. There is still some risk, but if your HP dmg cap and HP bonus% are high, 1-2% of boss health should be a mitigatable risk as Gladio was shown to be shaving off around 2% per dump by the end.
You can also choose to summon early and start spamming AOE whenever they are relatively even. It is also a viable strat to let them FR first, put them to 1% HP and then kill them after their FT is over. That is the 100% foul proof way other than employing full-time AOE attacks.
Needless to say Enna Kros would pretty much destroy this with ease. Do beware though that her LD is a massive ST attack.
A rather rare occurrence where they encourage you to enchant rather than go non-elemental if you don't go the path of holy/dark.