The answer that Sylvie came up with for the Emperor Class Mecha was similar to the answer that Nico had come up with for her Super Heavy Mecha. There were no heavy Thunder Guns, instead each shoulder hosted a twin linked light Gatling Mass Driver combo, with a third, freely rotating upper turret.
Then the front and back of the Mecha were each given wide dispersion Disintegrator emitters, to allow for a full circle of short range destruction. The main weapon in each hand was a triple Plasma Destroyer Battery combo, which could be locked to the side of the Mecha to allow blades to extend from the forearms for close combat if that became necessary.
As long as it was less armoured than a Crusader Class Mecha, any of the weapons should be able to destroy the target with a single shot, and there weren't many targets on the planet that were more durable than that.