An update to the Pokemon Bank app has today enabled players to get a Mewnium Z, and transfer old Pokemon into the latest game.
This means non-native Pokemon can be brought in from Pokemon Red, Blue, and Yellow, so hidden things like abilities, natures, and the like will become visible in Sun and Moon.
On top of that, The Pokemon Company has added a Pokedex and Adventure Records. The first will let people see info about their beloved pocket monsters, while the second will let owners see the stats about Pokemon caught over the entire series. Popping a Pokemon into the bank means you can get “Poke Miles” relative to the number of Pokemon they deposit, and how long they’re deposited for. At this point I don’t entirely understand what’s going on, so I’m going to paste you the blurb so you fans get the info!
When players deposit Pokémon into Pokémon Bank, they can receive Poké Miles relative to the number of Pokémon they deposit and how long they are deposited for. These Poké Miles can be received as Battle Points, which can be exchanged in Pokémon Sun and Pokémon Moon for various items. This means that players who have already got many Pokémon deposited in their Pokémon Bank accounts from previous games may find themselves getting a great number of Poké Miles!
Finally, players who access Pokémon Bank during 25 Jan – 2 October 2017 will be able to claim a limited-time special Mewnium Z, the Z-Crystal for the Mythical Pokémon Mew, which cannot be obtained through normal gameplay**. By giving Mewnium Z to a Mew which knows the move Psychic, it will be able to use the powerful Z-Move Genesis Supernova.
Source: God is Geek