Oh hell no. Mekton is a shade less complex than Battletech, but not by much. I don't know what I'd use for something like dozens of combatants, but I'd look into some kind of wargame and not an RPG.
Mekton has two mass combat systems, each intended for different sized battles:
Mekton Fleet Battles is the centerpiece of Mekton Wars 1 - Invasion Terra.
Mekton Z: The Movie is included in the Mekton Zeta Tactical Display.
Of the two, Mekton Fleet Battles is designed for battles with hundreds of mecha on each side, which covers Robotech nicely.