Ok so I did some testing. Rotom-C is just so one-dimensional. I don't really love it. Snorlax is a great Pokemon but it doesn't fit in with my "kill before being killed" team style and it basically just delays me losing a bit.
What I actually did succeed with was Swellow, surprisingly. It hits really hard, especially if I get hazards down. I used Endeavor in the last slot in case I get walled by Rhyperior, I can just drop it to really low HP so that Darmanitan can finish it off.
f u, v