[Eventing Question] How do I do a gender based rival?

I'm trying to do it like Pokémon RSE, where the rival is the opposite gender of the player, but I don't know how to do it. Any ideas?

Fixed, all I did was activating a specific switch when you choose boy, and another one for choosing girl, then, I created 2 pages, one that needed the "Boy Switch", and another that needed "Girl Switch", it worked