It exists but it was added to the Poke Bank for some reason. Sources that confirm this also state that this particular feature will not locked behind the purchasable boxes; it's completely free. Just gotta wait for Bank to update. It's weird but tolerable.Can anyone confirm whether or not the National Dex still exists? I've heard rumours that it doesn't but it seems like a weird decision for collecting every Pokemon to just not matter anymore and that would presumably mean no more shiny charm either.
Shiny Charm is obtained by completing the Alola Dex.