Humanoid like aliens that can ride mountable aliens? Think something like the locust from gears of war? I’m not sure how it work it just seems like a thing that’s worth a thought.
Commander abilities to impact the battle some more.
Call in artillery from a ship or bombing runs. Something like halo wars in a way
Something like leader powers. For those who don’t know check the link I put below and open the halo wars 2 tab, you can read all the leaders powers and specialities
Halopedia
Leaders, sometimes called hero units, are UNSC/Covenant/Banished player characters in Halo Wars and its sequel, each of whom feature specific units, traits, and abilities in gameplay. Some leaders can also be summoned to the field in-game as special units.