Hello everyone!
Right now, with the banning of Zygarde-Complete (Power Construct), the OU Council is now going to move on to looking at potentially banning or suspecting any other broken Pokemon or aspect available in Sun and Moon. For clarification, we are talking about the Pokebank metagame, not prebank. Pokebank will be the primary metagame in two months so we do not wish to waste time tiering a metagame that will be obsolete in two months nor do we want to waste time by not tiering for Pokebank until its release.
Some things currently on our radar are:
Aegislash
It seems not much has changed since Aegislash was banned in XY. Between its absurd stats, ability, and movepool, very few things can safely switch into it. Its versatility and movepool pose quite a strain on teambuilding and force teams to either use very specific answers or accept the fact Aegislash is going to be tough to handle. Although Aegislash is an incredible Pokemon, it could be argued it is not banworthy because it does have answers and is incredibly slow. It has also been presented with some potential nuisances in Sun and Moon between Mantine, the return of Hoopa-U, and Celesteela.
Genesect
Another former Uber, Genesect also poses similar issues to when it was originally banned in XY. Although, unlike Aegislash, it has been presented with checks between now and its banishment. Toxapex, Mantine, Volcanion, among other things were introduced in that timespan and give Genesect's formerly standard sets issues. Although it has more answers, it still has the ability to circumvent its counters due to its vast movepool, as well as the fact the ever spammable U-turn can be used to punish potential checks.
Greninja
Greninja, unlike the prior two, is a Pokemon banned in the ORAS meta rather than XY. Greninja was given a new incredible aspect to its movepool in ORAS that pushed it over the edge; Gunk Shot. This prevented former counters such as SDef Clefable from ever thinking about switching in. Greninjas movepool and speed are both incredible, alongside its ability, it could still be too much for OU, even with new checks in the form of Mantine and Toxapex.
Hoopa-U
Hoopa-U is another Pokemon banned in ORAS. It was released mid-ORAS and did not immediately pose itself as a gamebreaking threat. However as the metagame advanced, Hoopa-U advanced further. Its absurd power and incredibly STABs pushed it over the edge. Sun and Moon has presented us with multiple new viable Fairy types and an array of potential checks. Even with this, nothing can safely switch into Hoopa-U.
Landorus
Landorus-Incarnate returns to the metagame after being formerly banned in the later stages of both BW and XY. Boasting not only an insanely powerful Earth Power, but also coverage moves to hit just about anything it wants to, as well as Rock Polish to potentially sweep teams lategame, it is a force to be reckoned with at all stages of the game. It must be noted, however, that Landorus possesses only middling speed, as well as average defenses and a typing that leaves it open to a few common attacking types, meaning that it's definitely not close to impossible to stop.
Pheromosa
Pheromosa is the newest threat given to us from the Sun and Moon generation. Its incredible speed and power is comparable to that of Deoxys. Although its defenses are quite poor, it has some incredible advantages; Beast Boost and access to U-turn. Beast Boost can be customized to boost either Attack, Special Attack, or Speed upon killing a Pokemon depending upon how a user customizes their EV Spread. U-turn provides Pheromosa the ability to constantly pressure its common checks, between hazards and sending in a strong check of your own. Although Pheromosa is powerful, it has plenty of viable checks in OU at the moment, most notably Aegislash, who Pheromosa can not dent.
Please feel free to bring up anything else not covered above and give your thoughts on the Pokemon we covered. The Council will be actively watching this thread so please don't think your voice won't be heard should you post. Expect strict moderation; and please don't post one liners. If you have any questions or concerns, feel free to message the Council via PM.
Right now, with the banning of Zygarde-Complete (Power Construct), the OU Council is now going to move on to looking at potentially banning or suspecting any other broken Pokemon or aspect available in Sun and Moon. For clarification, we are talking about the Pokebank metagame, not prebank. Pokebank will be the primary metagame in two months so we do not wish to waste time tiering a metagame that will be obsolete in two months nor do we want to waste time by not tiering for Pokebank until its release.
Some things currently on our radar are:


It seems not much has changed since Aegislash was banned in XY. Between its absurd stats, ability, and movepool, very few things can safely switch into it. Its versatility and movepool pose quite a strain on teambuilding and force teams to either use very specific answers or accept the fact Aegislash is going to be tough to handle. Although Aegislash is an incredible Pokemon, it could be argued it is not banworthy because it does have answers and is incredibly slow. It has also been presented with some potential nuisances in Sun and Moon between Mantine, the return of Hoopa-U, and Celesteela.


Another former Uber, Genesect also poses similar issues to when it was originally banned in XY. Although, unlike Aegislash, it has been presented with checks between now and its banishment. Toxapex, Mantine, Volcanion, among other things were introduced in that timespan and give Genesect's formerly standard sets issues. Although it has more answers, it still has the ability to circumvent its counters due to its vast movepool, as well as the fact the ever spammable U-turn can be used to punish potential checks.


Greninja, unlike the prior two, is a Pokemon banned in the ORAS meta rather than XY. Greninja was given a new incredible aspect to its movepool in ORAS that pushed it over the edge; Gunk Shot. This prevented former counters such as SDef Clefable from ever thinking about switching in. Greninjas movepool and speed are both incredible, alongside its ability, it could still be too much for OU, even with new checks in the form of Mantine and Toxapex.


Hoopa-U is another Pokemon banned in ORAS. It was released mid-ORAS and did not immediately pose itself as a gamebreaking threat. However as the metagame advanced, Hoopa-U advanced further. Its absurd power and incredibly STABs pushed it over the edge. Sun and Moon has presented us with multiple new viable Fairy types and an array of potential checks. Even with this, nothing can safely switch into Hoopa-U.


Landorus-Incarnate returns to the metagame after being formerly banned in the later stages of both BW and XY. Boasting not only an insanely powerful Earth Power, but also coverage moves to hit just about anything it wants to, as well as Rock Polish to potentially sweep teams lategame, it is a force to be reckoned with at all stages of the game. It must be noted, however, that Landorus possesses only middling speed, as well as average defenses and a typing that leaves it open to a few common attacking types, meaning that it's definitely not close to impossible to stop.


Pheromosa is the newest threat given to us from the Sun and Moon generation. Its incredible speed and power is comparable to that of Deoxys. Although its defenses are quite poor, it has some incredible advantages; Beast Boost and access to U-turn. Beast Boost can be customized to boost either Attack, Special Attack, or Speed upon killing a Pokemon depending upon how a user customizes their EV Spread. U-turn provides Pheromosa the ability to constantly pressure its common checks, between hazards and sending in a strong check of your own. Although Pheromosa is powerful, it has plenty of viable checks in OU at the moment, most notably Aegislash, who Pheromosa can not dent.
Please feel free to bring up anything else not covered above and give your thoughts on the Pokemon we covered. The Council will be actively watching this thread so please don't think your voice won't be heard should you post. Expect strict moderation; and please don't post one liners. If you have any questions or concerns, feel free to message the Council via PM.