Troops can be upgraded in the laboratory, they will get stronger and better the more you upgrade them.
Each troop does have it’s own strength and weakness. Troops like the barbarian, archer and goblin are strong in groups but vulnerable to splash damage defenses like the mortar. Special troops like the wall breaker and healer have specific tasks. Some troops are flying troops, like the dragon and balloon. They can fly over the base and walls have no effect on them, special air defenses are their greatest enemy.