These are squads you can assign to individual units to assist them in battle. A unit with a battalion assigned to it will get Stat boosts and will be able to perform Gambits, a powerful attack that’s effective for breaking through the shields or armor of stronger foes like Demonic Beasts.
Battalions earn EXP along with their assigned unit who participated in combat. As they level up, the bonus Stats they provide also increases. The max level for each battalion is 5.
You can do this by accessing the Battalion Guild option in the Marketplace menu. You can go there on foot while exploring the monastery or you can access it from the Battle Preparation screen before starting a battle.
Check out the Battalion Guild once in a while, preferably after the story progresses every month. You can always hire new battalions even if you don’t have valid units to lead them. Some battalions, especially the higher level ones, will require higher Authority skill rank before you can assign them to that unit. Hired battalions are permanent assets to your army, unless until you dismiss them.
As a general recommendation, assign battalions to match up to their unit’s class. While there’s no problem assigning a Mage battalion to a combat class unit, giving the unit access to Gambits that will help them fulfill their role (damaging the enemy, tanking Damage, etc) will give you more versatility and reliability in the long run.
Battalion endurance is reduced whenever they attack, used in a gambit, or their assigned character gets damaged. Once their endurance is reduced to 0, they’ll withdraw. Their assigned character will lose the stat boosts that they provide until their endurance has been replenished again.
You can replenish your battalion's endurance by accessing the Battalion Guild option in the Marketplace menu. You can go there on foot while Exploring the Monastery or you can access it from the Battle Preparation screen before starting a battle. You can replenish the battalions individually but since the cost for replenishing them is quite negligible, you should always replenish them all in one go to save time and effort.
You’re free to unequip or re-assign battalions on your characters as needed. To do this, you have to do the following:
1. Access the Inventory
2. Select Battalions
3. Select the character you want to remove/re-assign the battalions from.
4. Press A to bring up the option to Unequip or Change.
5. When selecting from the list on the right side, you can press X to sort them by various categories.
6. Press A again to select the battalion you want to assign to the character.