[Spoilers]
I'm pretty sure I was like level 9 when I finished the battle but I'm also on easy mode. No one died for me though. Although my companions died when I tried to seduce the enemy and I'm pretty sure only Bradley and Hakkon can die while Feraldo and Skru'Vaks will just retreat. This was all I had:
Equipment:
- Full Sirthy-something (sorry idk the spelling) armor
- Thunder Cannon
Companions (These guys are probably the most important since they deal A LOT of damage)
- Bradley
- Feraldo (Alpha Wolf)
- Hakkon (Dick monster)
- Skru'Vaks (The Zareen + I told him to focus on attacking but you might need him to defend on normal mode, not sure)
Companions in the battle but were in the background:
- Cicero (The blue lizard in Bradley's ship)
- Pheonix (The soldier)
- Rylan (I didn't tell him to not join the battle)
Companions not present in the battle:
- Alastor (Made the armor and weapon)
- Arthur (Made the grenade with Katari)
- Katari (Mechanic)
- Sammuel (Pilot?)
My strategy was quite literally just spamming attack while my skill points were also stacked on strength. In my experience, I wasn't really hit until the companions died so you can focus on attacks. I also started the battle by throwing the grenade in immediately.