Next year will be Let's Go DLC that add in the entire Johto region to Let's Go Pikachu and Let's Go Eevee. This DLC will add in all Johto Pokemon and breeding and other Gen 2 era things to Let's Go. This means that no abilities yet.
In addition, until you clear the Region, you won't be able to use/bring your old Pokemon to Johto and Pikachu/Eevee will have their level and CP boosts "reset" while in Johto.

This will also add in more connectivity to Pokemon GO, so you can transfer Pokemon from the Johto region Pokedex.
Gold(Ethan), Silver, and Crystal(Not Lyra) will also be in the story and as opponents, similar to Red, Blue and Green.