Pokémon Bank has been confirmed for an update in “Late November”, meaning there won’t be too long of a wait to transfer your trusty team members from older games in the series — which hopefully will include Pokémon Gold and Silver on the eshop. Thankfully we don’t have to wait as long for this compatibility as we did for Pokémon Sun and Moon, which took a few months.

Meanwhile, Pokémon Ultra Sun and Ultra Moon are able to communicate, battle and trade with Pokémon Sun and Moon — with a few general restrictions. Pokémon, items and moves introduced into the new games will not be allowed into battles or trades with a copy of Pokémon Sun and Moon, meaning Rockruff with Own Tempo, Lycanroc Dusk form, Partner Cap Pikachu, Poipole, Naganadel, Stakataka, Balcephalon nor Zeraora cannot be used. What is interesting to note is that Totem Sized Pokémon that were present in Pokémon Sun and Moon are able to be traded and battled with these games — the new totems added to Pokémon Ultra Sun and Ultra Moon however are not.

Thanks Ben for the tip.
Edited by bobandbill.
Source: Serebii.