Some players may be eager to PVP with other players in the game, and without opponents and place some started to pick on random players, killing them and taking their possessions and cause conflicts. I would suggest reusing the pokemon stadium. Adding a command to allow PVP match-up with other PVP interested players. Once they are matched up, the system would send them to pokemon gym which have keep-inventory flag on and let them do the thing they want. This can reduce conflicts between players and have a better atmosphere without worrying random killers roaming around.
Our server scope is survival and aims to be less modded as possible, unlike those servers with tons of mini-games.
We've been trying to more fun features that will less likely affect the core survival gameplay, not saying a PVP system is bad, but it sounds like a mini-game system for me.