From my experience usually playing as the Lord Protector in my griffon runs the republics are numerous but their units are quite bad and mostly just spam 1007 light tank divisions (but preferably mediums if you can afford) with decent stats are usually enough to crack them and cut down their numbers to size until you can just battle plan just take as many entrenchment bonuses as you can without going grand battle plan for your infantry and focus on Aqulliea and Skyfall and defend against the North by using the ♥♥♥♥♥♥ terrain to your benefit (if you are having trouble filling the lines with inf just keep your templates to 16-18 width)

theres a glitch for griffon tanks going at hyperspeed, abuse that to its greatest extent