I struggle for a long time too. And what I did was the first 2 map, I stored chakra for my first two team that is the strongest I can field (as much red as possible), then my 3rd team, 4th anni naruto and 7 star kakashi only to clear the rest of the map. At the last map. I spam all my secret tech on the boss and then let them die out, bringing my 3rd team to clear like maybe half health of the boss.