How do Eevees evolve with friendship or affection in the wild? And why can’t you normally catch wild Eeveelutions except for Espeon and Umbreon in Alola?

Friendship (or more accurately and commonly known, happiness) evolutions are perhaps the easiest type of evolution for pokémon to achieve in the wild, as these rely less on a pokémon’s environment, age, or experience but instead on their state of mind. All a pokémon needs to do is achieve a state of complete happiness with themselves and their lives—which, yes, is easier to do when in the constant care of a human but is still possible in the wild. This should also explain why espeon and umbreon are so easy to find comparatively. It’s not that the others don’t exist but instead because an eevee will be more likely to evolve into either of those in their native habitats than the others. That and the other evolutions require additional environmental factors that aren’t really present within the Alolan nesting grounds on Akala, so if an eevee wishes to achieve an alternate evolution, they would need to journey far from their home fields. Not all of them go home, either: many wander alone or congregate in territories far too remote for humans to reach.

As for sylveon, though, that’s also possible, but it’s less common than an espeon or umbreon evolution. Instead, an eevee needs to be affectionate … with a mate. This also explains their rarity in the wild. They’re not actually rare; they’re simply in breeding pairs and thus avoid contact with humans as vehemently as possible.