Just a reminder that providing specifics on, sharing links to, or naming websites where ROMs can be accessed is against the rules. If your post has any of this information it will be removed.
Welcome to PokéCommunity! Register now and join one of the best fan communities on the 'net to talk Pokémon and more! We are not affiliated with The Pokémon Company or Nintendo.
first thing you need to know is that to make a gym battle you need to make a script
If you want to make another Gym battle, you go make a script and there you go...
Only problem is, you wouldnt be able to see the badge in your trainer card
Im assuming you know nothing about rom hacking, or at least scripting, so if you wanna get into it, just search for tutorials here on PokeCommunity, I suggest you start with Advance Map and Scripting
Sort of. You can insert events into the game and call them Gym Leaders and have them either not give badges or give their badge as a regular item that can't be sold. I don't know if adding extra gym badges is possible yet, but I wouldn't doubt it.