Correct:
1. Combat Troops - Standard term for military units in combat.
2. Fighting Troops - Troops actively engaged in fighting.
3. Armed Troops - Troops equipped with weapons.
4. Troops for Fighting - Troops designated for fighting.
Incorrect:
5. A Fight Troop - Use "a combat troop" or "a fighting troop" instead.
Summary:
* Use Combat Troops, Fighting Troops, Armed Troops, or Troops for Fighting.
* Avoid A Fight Troop.