The plethora of classes available for each unit in Fire Emblem Engage gives players a ton of options when building team compositions for the tactical battles ahead, but the best character synergies support a wider variety of strategies. Classes are divided into the frontline and backline, organizing the player's focus into which members of their team work best on the offensive in relation to who functions better as backup. Although promotions and upgrades to weapons also exist to deepen the experimentation of team builds for players, having a solid foundation first sets up success during the early stages of recruitment in the narrative.
https://screenrant.com/best-team-compositions-fire-emblem-engage/