Pokémon GO/Pokémon storage

Tracking
When walking around the map, in the bottom right there's a bar that will show you nearby Pokémon. If you have the Pokémon registered in your Pokédex it'll show up in full colour, otherwise only its outline will be visible. The number of footprints shown below the Pokémon gives an indication of their distance, with three footprints meaning the Pokémon is at some distance. If you're moving in the correct direction, you'll notice the footprints reduce. Once there are no footprints, the Pokémon should appear momentarily. Even if two Pokémon have the same number of footprints showing, the ones in the first row are the nearest, and in each row the leftmost Pokémon is the nearest. Hence, the top left Pokémon is the nearest, and the bottom right Pokémon is the furthest away.

Stats
Each Pokémon has a number of statistics associated with them which defines how strong they are in battle.

Power Up
Powering Up a Pokémon requires Stardust and Candy to increase a Pokémon's level by one.

Transfer
You can transfer unwanted Pokémon to Professor Willow for 1 Candy. This is effectively giving away the Pokémon as it cannot be undone.