So basically, that robotic armor is actually him even though citizens all think he died during the war.

Anyways since there is the shop, once we go further with the story his shop will be empty.

He will fight us in Waterfall before or after Undyne.

He wields his hammer of course, enhanced with chained, movable forward spikes for long distance.

On genocide he has a final attack that is somewhat a sequence similiar to TS!Swap Asgore's.

He turns with his back towards us and blades come out of it being launched towards us. His eyes become white and visible within the armor.

The armor breaks as the attack goes on and then after its broken we can see that Gerson killed himself with the blades off his back.

So we don't get any EXP for it as he dies before we get to hit him.

Thought its a better story point conclusion for him than anyone else considering he knows we cant fight him in his shop, he also knew if he dies with his special attack you won't get any EXP.