I actually had a pretty crazy (probably bad unless it goes through careful balancing) idea of implementing Yggdra Union-style cards, but instead of special moves and movement, each of those cards is like a Days of Ruin CO that provides passive bonuses to all allied units within a commander’s range of influence. The idea is that each commander has several cards and they can swap them out depending on their strategy (and each card has a set limit of turn uses per battle, so you can’t cheese using only the overpowered ones). I thought of quite a few ones xD I’ll spare you the more normal ones, but here are the gimmick ones.
+4 Mov. -2 to all stats, and can’t make attack actions during player phase.
Small range of influence. +4 Atk, +3 Spd, -5 Def, gain Pass ability.
Small range of influence. +3 Def during enemy phase for every allied unit within two squares of the commander.
+3 Atk, +3 Mag for every female unit under influence.
Same but for male units.
And the crazy one, probably enemy-exclusive, held by the boss of some Victory or Death-like map:
Very large area of influence. +0.5 Atk, +1 Def for every unit under influence. -1 Mov.
(The idea is that the commander is at the center of the formation, untouchable, and the way to make him vulnerable is to kill most of their army first)