In episode 8, The squadron stated that their abilities were useless in battle with Adolf Reinhardt and Isabella R. Leon shown to be the only ones with combative creatures from their surgery. It's weird that they're being sent to Mars to fight mutated humanoid cockroaches and there are only 2 members of the German squad that are battle ready.
A possible explanation would be Adolf's ability himself. Adolf's ability was that of an electric eel. He can shoot electricity around with the help of his throwing knives. By fighting alone he won't have to worry about friendly fire or accidentally injures his subordinates from the spark. That's why his squad requires only a few combatants.