I've seen people asking about unlocked hairstyles/clothes etc between the existing gender settings (because so little about the player sprite changes between genders otherwise) and that's a really cool idea, it'd also be really inclusive to have a gender-neutral setting that has story characters use "they/them" and removes words like "girl" and "boy" when referring to your player character. Maybe the big gender stuff with the rivals in Hoenn and Sinnoh could be split, like a non-binary person gets May and Lucas or Brendan and Dawn? Off the top of my head May would be the easier Hoenn rival to rewrite because in Gen 3 she doesn't immediately comment on you being a boy the way Brendan comments on you being a girl.