Iron Age or Industrial Age? And is this 1 I A + more advanced units? Or 1 I A unit as in that unit and 7 empty slots? Or 1 I A unit duplicated into all 8 slots?
Iron: Legionare
Industrial: Howister
I find up until Progressive the heavy units to be pretty solid on auto battle. Of course they'd be useless against artillery but there's not a single typing that'd be able to take everything down. One would still have to negotiate certain battles if you only use one unit typing
In addition I already most of the time use heavies instead of light units when it comes to double waves (unless I'm facing only ranged or only fast). I know that the heavies will be able to take down both what the light units can as well as the heavies own portion. But i cannot do the same in reverse.