Battalions were a brand-new gameplay mechanic added to Fire Emblem in Fire Emblem: Three Houses. This would involve assigning a group of soldiers to a unit that could be used in combat.
Each battalion excels in a weapon category, but the endurance and effectiveness of a battalion would vary based on its ranking.
Players could deploy battalions in battle by selecting «Gambit» if they had one assigned. In Fire Emblem Warriors: Three Hopes, battalions can be purchased, but they're much more simplified than their Three Houses counterparts.Since Fire Emblem Warriors: Three Hopes uses hack-and-slash gameplay, combat is fast-moving and relies less on real-time strategy.
However, units need to rank up their Authority if they want access to the best battalions Three Hopes has to offer. Unlike in Three Houses, equipping a battalion will reduce the damage taken from certain weapons in Three Hopes.Read more on gamerant.com