Stop Pokémon from spawning in specific areas?

It's as the title says. A bunch of friends and I are playing on a private server with quite a few mods. Some of them are not Pokemon fans and do not care for Cobblemon at all, but Pokemon keep spawning in their castle, and they are overturned mobs to someone without a Pokemon of their own. So I'm wondering if there are any items to stop the spawning in a radius or something.