Alright, so @drugwars said:

What we can advise you is to build different types of units if you are aiming to let them go into a Battle, because each type of unit will be able to attack only once each round.

If that's so why did units with total Att 454 and total Def 284 kill bouncers with total Def 750 + 144 + 40 while surviving total Att 846? Any first striking abilities that do not let units deal their damage? A sniper can take out 3 gunmen's Def, the Bazooka can blast them all, but then the rest should have survived.