Module encounters 

Encounters endpoints group

Modules

encounter_condition

Conditions which affect what pokemon might appear in the wild, e.g., day or night.

encounter_condition_value

Encounter condition values are the various states that an encounter condition can have, i.e., time of day can be either day or night.

encounter_method

Methods by which the player might can encounter Pokémon in the wild, e.g., walking in tall grass. Check out Bulbapedia for greater detail.