Well, ground battle can go one of several ways, depending. For generic purposes, could use the following list for land types
Commando
Light infantry
Heavy infantry
Walkers
Tracked
Hover
Those are basic class types, and then give bonuses based on type.. like, walkers would be better at combat vs Tracked Vehicals, but poor vs Hover ones. Hover would be weak to Heavy infantry, that would in turn be weak to light infantry, that would be weak to tracked. Commando units can be strong vs buildings and defeences like that, but not to great in pitch combat.
I can come up with a more detailed one. Want me to do it here? or via an email or something?