Battles take place in a 2D side view similar to Advance Wars
, only you don't really fight in battles as much as you influence how they'll play out. Rather than moving large armies, you are really just moving one general who represents a larger army following them. You're only allowed to attack once per turn, so the key to battles is knowing how to align your units in formations that allow the most number of units to attack in one turn. Any units that form an "X" formation around a male character or a "+" shape around a female character can join them in battle. Your goal is to get as many of your own units into a battle, hopefully giving you the advantage in numbers. Each turn units recoup any troop loses, though by pulling in numerous units into a battle you can usually hit the enemy before they can restock, making your path to victory that much easier.
Aligning units in the best formation is harder than it sounds given the claustrophobic battlefields and the fact that enemies can also pull units into battle. Even if you manage to pull everyone into battle, you also need to contend with the "Paper-Rock-Scissors" relationship between weapons. Each of the three basic weapons (axe, spear, sword) is powerful against another weapon and weak against another. Even if an axe-wielder is outnumbered, if the opposing units have swords, the axe still has a chance.
Rods and bows are eventually thrown into the mix and share their own special relationships. While the axe/spear/sword hierarchy is easy to understand, rods and bows have different strengths based on how they're used in battle. On offense, both can trump any other weapon, though on defense they are weak. Enemies show up with bows and rods really early in the game, which places you at a disadvantage early on.
Battles are also influenced by pressing Left or Right on the D-pad during battle. Pressing Left places your units in a defensive state, while pressing Right makes them more aggressive. Playing with an aggressive stance drains a meter that allows you to use you card ability, though it can give you a massive boost - even allowing "weak" weapons to defeat "strong" ones.
Yggdra Union is a fun strategy game, though the trial-and-error gameplay and numerous restrictions may not appeal to everyone.