If you don't have a good Unique DPS (any of Twins, Enna Kros, Astos etc actually works), you can instead use a Unique weapons character that is speedy enough to start first. And then get a friend unit that is DPS focused.
At battle start just have the throaway character use the Raines calls, then swap to your friend unit and use its BT+.
You can just use Deuce to charge the FR in that scenario.
I didn't use any throaway character in my run, instead I used an Aerith friend as a throwaway just to reduce the turn count to 1.
Setup
Everyone has U2. White Crystal U6 is also equipped. The rest hardly matters.
Twins no UW FR50 (Raines LDCA)
If you don't have twins, use the throaway strat outlined above
Deuce 5/5 UW FR50 (Lunafreya LDCA)
Deuce must be in party slot 2
CoD no UW FR50 (Seymour LDCA)
I think Ifrit summon would be a better choice over Brothers
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