How does def/atk tactic skill work?

It has to be the movement type. So 2 or fewer infantry units. It works best in a mixed team.

I asked this same question so I know the feels. XD

Why are ppl so dumb with this skill...

You misread it. It says if you have 2 OF THE UNIT WITH THE SAME MOVEMENT it wont work. So if you have 3 horses (they all have the same movement) it wont work. But if ur team is a horse, 2 infantry, and an armor, all will get the tactic. xdddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd

The wording is confusing, to say the least. Basically you can't have more than two units that have the same movement on the same team for it to work, ex. having four infantry units, it won't proc. Basically don't have more than two infantry, armor, cavalry, and flier on the team.

The ≤ 2 refers to number of units, not movement type. So if an infantry unit has this skill, you can only have up to 1 more infantry unit on your team for it to work. If a cavalry unit has this skill, you can only have up to 1 more cavalry on your team for it to work, etc.

It works when you have 3 infantry and 1 armor too, but the buffs only apply to the armor bc there is one of that movement type.

Its the movement type, you team must have in maximum 2 in the same movement, 2 infantry, calvary, fliers and armor.