This month you'll be able to get your hands on either Reshiram (Moon/Ultra Moon) or Zekrom (Sun/Ultra Sun). The details of the two are as follows:
Level: 60, 100 (Sun/Ultra Sun)
Hold Item: None, Gold Bottle Cap (Sun/Ultra Sun)
Dragon / Fire
Level: 60, 100 (Moon/Ultra Moon)
Hold Item: None, Gold Bottle Cap (Moon/Ultra Moon)
The event runs in Australia and Europe from the 5th of October until the 21st and is being run over Nintendo Network. In the US the event begins on the 19th of October until the 28th and you must go to a Target code and obtain a code to take part. For those of you in Canada you'll be sent a code through the Pokémon Trainer Club Newsletter.