Well the LPSO is the only consistently social octopus. "Octopus city" was actually 2 cities (the second one being discovered in 2016) and they were groups of about 15 gloomy octopuses. There are a couple of other examples of octopus sociality but on a species-wide level only the LPSO can be comfortably described as social

Almost all octopuses are cannibalistic but Abdopus have also been found living close to and tolerating each other