Don't need much. I laugh (internally) at the people who are all geared out with poles and shit for their "epic 5k ultra marathon" hobby jogs.
Running is a simple sport and running regularly is the only key to not being a faggot poser regardless of what surface/venue. Speed and stamina built on road and gravel runs will transfer into the mountains -- with some strength/hill work mixed in.
I'd rather be a fast guy in road shoes and split shorts & look out of place than look like some larpy kitted out bitch who thinks it has to be some overcomplicated shit with specific gear, the kind of bitch who just *has* to run with gels and hydration no matter what. Loads of these people in the trail scene, loads of them in my local area. These people, they're not runners -- they're always sure to specify they are "trail runners". I think they hope that this distinction will serve as an excuse for why they're so slow.