Pixelmon Mod

I'm trying to make Gyms spawn in the wild. I've been changing the "structures.json" file so that the gyms will spawn random in the given biomes which works now. The only problem is that they spawn without NPC's inside of them. Has anyone ever tried this before and worked out the way to add the npc's in "standalone gyms", or someone who knows how I could make this work? Please contact me on discord or answer on this topic