Pokémon GO is a free to play game, and as such has numerous aspects that require purchasing using in-game currency.
|There are various purchasable items that you can obtain in the game. While you can obtain many of these items through levelling up your player and by visiting PokéStops, you can outright purchase them using PokéCoins
The items you can purchase are as follows
|PokéCoins can be somewhat tricky to get. The easiest way to get them is to simply purchase them outright. However, if you hold multiple gyms, then once every 21 hours you can get a bonus. You will get a number of coins of 1 coin for every 10 minutes a Pokémon defends a gym, with a cap of 50 Coins per day.
However, as that is limited and you may wish to purchase multiple things to expand your Pokémon capabilities, purchasing the PokéCoins is the next best option.