It's a great job that edain team makes every unit unique by giving them formations or skills, but I can see that some units have this same formations so I want to share my ideas about formations with you:
First for all I want to drop out porcupine formation couse it unless (not giving any bonus and makes units immobilized).
- gondor spearmen get "hold the gate" formation or skill which gives them 15% of armor and damage against enemy in front of them and -30% armor against enemies from other sides ( about visual side more soldiers should go to first line ).
-rohan farmladns get "fighter for rohan" passive skill - men of rohan fight not only for country but for their women and children - they have 15% (or lower) that they will fight for 5 seconds after their health bar depleted.
-meduseld wardens get spear throw as a skill which knocback enemies (or not) and slows them down.
-isengard pikes get "pikes down" skill which give them 20% damage against cavalary and monsters but -20% armour against swordsmen ( about animation you can use this one that is used by tower guards and iron hills spearmen formation.
- dale sprearmen get "city watch" skill (or passive skill) that allows them see hidden units and gets small bonus against them.
So what do you think about this idea ?