From Krama: 

Okay - to start, some context. There's typically two approaches to CB. You either build a team with unkillable/block damage, which typically involves some pretty elaborate manipulation of turns through TM boosting, or you build a "standard" team. In the former case, your goal is to reach the minimum speed requirements, and then max out on damage. In the latter case, you almost always need some combination of Ally Attack or Counter Attack, or both, and the goal is to survive as long as possible - sometimes well over 50 turns (one of my early 1-key UNM teams routinely lasted 60+ turns).

You don't really have any pieces at all for the unkillable/block damage one, so we'll focus on the second option.

So unless you got maneater or another unkillable setup ally protections and 100% of it uptime is your best bet.

Probably just a standard 1:1 rotation with:

• Geomancer
• Hotatsu or Ghrush (turn off A2 and A3)
• Toragi
• Brago
• Grizzled Jarl (slowest)

Not ideal, but should probably get you a 1-key NM at least.