"Outbreaks have been spotted around the world, invading the habitats of other Pokémon! Investigations have pointed out that these occurrences last for approximately 4 hours, the cause still remains a mystery …"—
An Outbreak is a randomly occurring in-game event. It will create a spawn for a random rare Pokémon at a random location. Said spawn of the random Pokémon will be more common than its regular spawns. Normal Outbreaks are active for usually 4 hours; however, they can also created by the Staff team with a set Pokémon and appearance time.
Outbreaks in depth
Pokémon and Spawns
Outbreaks appear randomly and are not announced beforehand. They normally last for 4 hours and take a random Pokémon out of a set of Pokémon, shown below. Those Pokémon are usually rare or very rare and do not necessarily have a current spawn place, which means that Alolan forms, which were already catchable in the past, can also appear. Outbreaks will be announced in-game with a system message in every chat and in Discord where the Reborn Bot will write an announcement in an extra channel.
When there is an outbreak on the Silver server there is also one in the Gold server as well, but the Pokémon and spawn location won't necessarily match. Outbreaks can also be created by Staff with a set Pokémon and duration.
The spawn rarity depends on the current, lowest, rarity of the Pokémon and decreases it by one. All Generation VII spawns seem to have a rarity of Rare.
The following Pokémon have already had a spawn in an outbreak and can appear again. Their spawn tier refers to their originally spawn tier which is not influenced by the outbreak.