Cosmog is a new Psychic type Pokemon with the ability Unaware. It shares a similarity with the legendary Pokémon Solgaleo and Lunala.
There are a few key features you'll want to be mindful of while on a hunt. The first is Pokestops. These are buildings, landmarks, and other objects of interest that grant you bonuses, eggs, and Pokeballs when you pass by them. Pokestops are marked by blue boxes that turn into blue Pokeball symbols when you approach them. The symbols turn purple when you've collected their items. These are important if you want to keep stocked up on Pokeballs. Eggs are also good to have, because they hatch after you walk a certain distance (2 kilometers seems to be the minimum) and they're currently the only way to get Pokemon from Generation 2, like Cleffa, Igglybuff, Pichu, Togepi, Elekid, Magby, and Smoochum. Pokemon Go's GPS data have improved in reliability and accuracy with recent updates to the point you should have no trouble hitting stops.