According to the Japanese Pokémon Global Link website as reported by Serebii.net, thousands of people (5,954 to be precise) have been hit with bans from Online Play (Game Sync, Battle Competitions, Rating Battles, Global Missions).
Banned users will see error code 090-0212.[1,2]
The Pokémon Company has announced that they will continue their pursuit against people with edited save data.[1,2]
We urgently recommend not going online until we have more information on how these bans were triggered.
The latest Pokémon Bank update has been released. Those who have Pokémon Sun and Pokémon Moon can receive Mewnium Z, a Z-Crystal exclusive to Mew. Additionally, Pokémon Transporter has been updated to support transferring from Generation 1 virtual console games.
Transferring Pokémon from generation 1 virtual console games will come in a separate update for the Pokémon Transporter.
In related news, @SciresM did some data-mining and found the text for Pokédex entries, which can be read below:
(Pokemon Sun/Moon covers 1)
Nintendo has released a patch for Pokémon Sun and Moon introducing the following game balance fixes 2:
Battle videos recorded before applying the update are incompatible with this patch and will be unplayable after installing it.
With regards to game hacking, this may break ROM hacks, depending on whether or not the ROM hack modified the game's executable. If you are playing such a ROM hack, you will either need to refrain from updating or wait for the author to update the hack. Save editors like PKHeX are unaffected.
@SciresM's SMPatcher has been updated to version 1.1 to provide compatibility with the update, and can be downloaded here 3. If you are new to SMPatcher, it will modify the game executable to make QR scanning and PKHeX importing much similar. In order to use it, you will need to have CFW, which can currently be installed using the latest firmware. The recommended installation guide can be found here. Here is a list of patches that SMPatcher can apply to Sun or Moon:
Pokémon Sun and Moon Official Website