Iroha FR is currently our best "generalist" FR that allows super charging of the FR bonus to sky high percentages. This strat abuses this mechanic along with Lunafreya's Quick Prayer
Setup
Party 1: Cid Highwind, FR20 with 5/5 UW. Prishe LDCA
If you don't have Prishe, use Alisaie LDCA
Party 2: Iroha, FR10 with FR. Her high armor is 0/3. Cait Sith LDCA. If you don't have Cait you can try a call that lands HP damage up debuffs such as Raijin, Seymour or DKC
If you don't have Iroha, Ursula FR works as well but you can only get 3 Cid EX out of it, not 4
Party 3: Lunafreya, FR30 with BT+, 5/5 UW. Kurasame LDCA. The call can be swapped with any call that lands HP damage up debuffs.
Bahamut summon
Lunafreya friend with FR30
0:00 Turn 1 with Lunafreya
Reset until you get turn order of Luna, Iroha and Cid
Luna uses the first 2 LD to charge FR and summon Gauge by alternating between s1 and s2 or EX
After the second LD use, spam S1 until she has 1 charge remaining.
On her third LD use, use BT+, and then Heavy prayer Cid Highwind
Then use her final LD, use attacks to charge summon meter, then use Heavy Prayer on Iroha and AA before ending her turn
4:19 Turn 2 with Iroha
LD LD LD Cait LDCA and then FR.
5:18 Hypercharging the FR bonus
Swap Cid out for Lunafreya friend. Spam S1 five times.
6:03 Cid is ANGRY
Really check out his insane damage. EX, Summon, Prishe LDCA, EX, EX, EX and boss is dead.