I'd focus on it being pure frontal assault against heavy porc. Not "assault-riot" or whatever. A very specific purpose: The enemy has heavy hyper-dense porc that needs to die. The Sumo may or may not survive the encounter, but the Doomsday almost certainly won't. A punishment for the hubris of thinking that heavy defenses will protect your base.
Now, the undesired stats: stomp reconfigured as a single-target attack with a long range, extremely-long recharge, and a huge hang-time so it's useless except against large buildings or stupidly immobile targets. Like assault/artillery, except the Sumo
is the projectile, which lets it go through shields unlike conventional artillery. I guess I just contradicted my "pure assault" by saying "assault artillery" but you know what I mean.
As for the guns? I don't care, something assault-y. Maybe slow Buoy disruptor balls or some kind of light d-gun or something.
This would be pleasantly different from the Jack that does best against low-grade porc and riots and tearing down the enemy eco/comm/whatnot.