Duo run may sound quite challenging but on the contrary, Reno FR benefits from fewer team members. Fewer team members means lesser player turns which also means longer force time.
Auron is off turn of choice here for few reasons. Firstly he has delay in his EX which helps to deal with the yellow aura on this stage. Secondly, his LD and counters ignore defense which helps since this party lacks support auras. Thirdly his damage is pretty evenly spread across both bosses, which helps keep their HP even.
You could use Galuf over Auron, but in that case you also need to give Galuf a call that can AoE delay, which means you lose out on the Garnet call
Timestamp
Party setup at 11:01
Reno has 0/3 high armor, no UW, FR30, Ramza LDCA. If you don't have Ramza use any other call that delays 1T. CoD base call is good budget option. DKC Call is another
Auron has 5/5 UW and 3/3 HA, FR10. I gave him Garnet call. Alternatives are Krile or Ashe. Or you can give him a Cyan call and pop that at 999% force bonus
Remove all passives that have Speed in them, and also Auron's Banishing Blade Lite.
0:00 Setting Up
Just spam S2 and EX on Reno
Auron uses LD once then spams either S1 or S2. You can also use EX but when you get close to 100% force gauge SAVE his EX!
Use Garnet call when you are around 80% force gauge for the party enchant.
2:43 Force Time
At 100% Force time, use Reno AA and then FR. Welcome to BIIIIIG damage time. Here, use Reno LD or EX when it's up for bigger damage. Auron should also spam his LD. Seriously there's no need to save it.
Watch the Force bonus quickly add up and Auron's counters get amazingly high
At 79% and 19% boss will get Yellow aura. Use Auron's EX or Reno's call to quickly dispel the aura.