Quoted By:
I have a Pokemon OC I used for some PbP stuff a few years ago. He eventually came to be the Gym Leader of Lavender Town so I guess I'll just describe that since he was a self-insert.
Ghost type gym
Aegislash, Golurk, Sableye, M-Gengar
I hated the Radio Tower in Gen 2 and designed the gym based around that. I reasoned that there were huge graveyards in the foothills beyond Lavender, and had my gym built out there. Visitors would be guided by trainers to protect them from angry ghosts. The gym itself would be pretty austere, mostly just a clearing surrounded by headstones and spectral torches. The puzzle portion would be for the challenger to navigate through the graveyards to find the 'gym' in the first place.
I came up with the idea that the entire place would be covered in 'Ghost Terrain'. It would boost the power of Ghost moves like the other terrains, and also apply a global Pressure effect to all non-Ghosts.
Shadowbadge, probably look like some generic casper ghost thing. I suppose a shitty challenger could earn a badge by proving their affinity with ghosts somehow. Phantom Force deserves to be more common, I think, so maybe that would be the TM.