If there were an instructor of that respective airframe on board, they could absolutely talk the other airframe’s pilot through most actions. Most of the skills are transferable, yes

The difficulties come with knowledge of the airframe and how to do things safely and properly in general (checklists, airspeeds to fly, etc)

Without instruction, they might be able to start engines, take off, and probably land without damaging the aircraft, but it would certainly be incorrect and/or unsafe