I want to make a ROM hack of Crystal that simply adds rematches for the 16 Gym Leaders and nothing else. No extra QOL, no muh level curve fixes, no Houndour in Johto etc. Just Gym rematches.

Here's the thing, I want the hack to feel as vanilla as humanly possible. I feel like the one thing missing from GSC is Gym rematches, it feels like they should've been in the base game, so I want to add them myself, but I don't want it to feel like a ROM hack if you know what I mean. So my question is, how should I go about doing it?

1) How will rematches actually be handled? I was originally leaning towards the Pokégear, but remembered the 10 number limit. If I went this route it would cause 2 problems: it would make regular trainer rematches redundant, and you wouldn't be able to rematch all 16 Gym Leaders and progress through their increasing teams without deleting numbers, which would reset their teams back to the first one.

2) What should the actual teams be? I want to avoid overlaps as much as possible, and no fanfic shit like Legendaries and Starters. And no just giving them random Pokémon of their specialist Type, they must fit the theme of the team (e.g. no Crobat on Falkner)

My idea for the 1st problem is to just have them wait in their Gyms as normal, but on certain days of the week and at certain times, if you talk to them they will offer you to battle. I'm thinking of just pulling the rematch times and dialogue from HGSS and using that to stay as close to vanilla as possible.

I will upload an infographic as people suggest ideas for teams throughout the duration of this thread. Thanks!