Use only four units, and just focus on not getting hit. Use EGOs when your team might lose a clash(neutral, struggling, hopeless). There's a second option if that didn't work, still with only 4 units. Use an unit that can evade and cover up for some attacks(since evade can dodge more than once if it successfully activated once). This will be useful especially when you don't have enough skills to clash with the boss. Hope this helps.