Since no friend unit is allowed I made do without any FR charger and charged the FR the slower way
Freya holds a Zack LDCA to inflict Lock on. You can also use Celes LDCA. This protects you the first 3 boss turn as she will be dodging every attack in the air.
Kain (1/5 UW) holds a Leo LDCA for the aura, if you don't have it, use Seymour.
Terra (5/5 UW) uses a Gladio LDCA to neutralize the boss recast attack. If you don't have this, use a WoL LDCA.
Timestamp
Party setup at 10:06
0:00 Starting out
Kain uses BT+ then LD and LDCA and then jump.
Freya uses AA twice, then Zack call then jump
Meanwhile Terra just use S2 S1 to pass her turn.
Once both dragoons are in the air you can go LD with Terra and Meltdown spam until Summon is ready.
2:47 Summon Mode
This is to keep turn count low and to freeze the boss FR gauge. Relaunch Kain and Freya while in summon mode.
Use Terra LD before exiting summon mode
Then LD Meltdown until FR is 100%
6:17 FR and BT mode
When FR is 100% use FR, LD, Gladio LDCA. Pop BT mode when FR has 8 turns remaining.
Once you come out of BT mode the bosses will get 3T each, but Terra will be protected by the Gladio LDCA. Bosses will get melted by Kain and Freya's spears while they take their turns
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