Mech Suit:
Main body: Marvel Legends Hulkbuster Ironman (heavily modified)
Chest emblem: Barrel Roll glider
Chain gun: Tigerstorm Helicopter
Arm gun: Single Pack Claws gun
Head emblem: Venomous Maximus staff

Serpentor:
Head: Scalpel
Torso: Sand Viper
Shoulder pads: VvV Overkill

I figure that Serpentor is the kind of commander that joins his troops on the battlefield and revels in the thrill of war. His air chariot is just fine for more ceremonial events, but for battle I figured he needed something a bit more durable.

The suit is a walking tank, the armor durable enough to sustain a direct blast from the main gun of a Joe MOBAT or a Cobra HISS and keep going. In addition to the formidable armaments, the suit possesses enough strength to tear through light armor with its mechanical hands. From inside, the comm system allows Serpentor to maintain constant contact with his troops, ensuring that even in the heat of battle, he remains in full command of his forces.