To be fully honest, I don't know the best way of going about this... but would it make sense to give all H1 Aavegotchis a general increase in rarity score? My thinking is that "rarity" is inherently tied to all of H1 based on when they were summoned and how early someone participated in this dope project. If anything should be considered rare, shouldn't it be the first 10,000? They will forever be "rare", so it doesn't seem out of the REALM to give a tiny boost of rarity score based on the haunt number. I suppose it could apply in the future as well, whenever we do H3.
Perhaps one solution would be adding a rarity increase to the Background item that all H1's received and can equip. Or maybe that isn't even possible and there would need to be a new item dropped to all H1 gotchis... just spitballing and I know someone smarter than I would be able to come up with a solution.
Just my thoughts. If we are talking "rare", why not include a boost based on the Haunt they belong to. Your thoughts?