>>53767496I'd ditch Kingdra because you get it lategame and it's quite middling offensively unless you want to set up rain all the time.
For the campaign you should worry about offensive variety more than resistances, since you'll be spending most of the game delivering OHKOs against fodder. So it's good you already have a ground type since nothing else hits electric.
For this core 3 that you have, I would add a fighting type so you can hit normal/steel/ice, an electric or grass type, and a dark type.
Fire type hits steel/grass/bug/ice for SE, which would be covered anyways by using a fighting type + scyther, so I don't think having one is necessary here. But having a dark type like Houndoom, the fire would just be a nice bonus.
