>>39347752For now these are only rolled out for events. For the Chinese Lunar New Year you linked with 3 more people, were teleported into alternative Abundant Shrine, turned into Pokemon and fought waves of progressively stronger mons 2v2. At the shrine building you could turn into whatever your team had defeated, finally you fought Entei.
These are expected to become permanent relatively soon, with loot like Hidden Abilities and non-Uber legendaries.