From Bulbapedia, the community-driven Pokémon encyclopedia.
In traditional Pokémon games, if you want to make your Pokémon stronger for battle, you generally have to make it gain experience through battle. In Pokémon GO, however, Pokémon themselves do not have levels or gain experience. Instead, you directly Power Up and evolve your Pokémon using two resources: Stardust and Candy. Powering up or evolving your Pokémon will increase the two stats they have: Combat Power (CP) and Hit Points (HP).
Combat Power (CP) is a measurement for how much damage your Pokémon will do in battle. The amount of CP any Pokémon starts with is randomly determined when it is caught or hatched, but different species of Pokémon will have different maximum CP values. Your Trainer level partially influences the CP of Pokémon you encounter, so leveling up your Trainer can help you naturally find wild Pokémon with higher starting CP.
Hit Points (HP) are an indication of how much damage your Pokémon can receive in battle before fainting.
Stardust and Candy
The two resources you need to Power Up or evolve a Pokémon are Stardust and Pokémon Candy. Stardust is only required to Power Up a Pokémon, while Candy is required to both Power Up and evolve a Pokémon. Usually, powering up a Pokémon requires a very small amount of Candy (but on the other hand, you can Power Up a Pokémon multiple times), but evolving a Pokémon requires many pieces of Candy.
There is an important difference between Stardust and Candy, however. Whereas Stardust can be obtained in many ways and used to Power Up any Pokémon, Candy comes in varieties specific to every evolutionary line and can only be used to Power Up or evolve a Pokémon of that line.
Neither Stardust nor Candy is purchasable in the shop and must be obtained in the following ways:
- Catching a Pokémon: awards 100 Stardust and 3 Pokémon Candies specific to the species caught. Catching an evolved Pokémon still awards Pokémon Candy for the basic form of that Pokémon's evolutionary line. For example, catching a Metapod would award three Caterpie Candies.
- Defending a Gym: awards a bonus of Stardust (as well as PokéCoins) for every 21 hours that your Pokémon is defending your team's Gym. You may only leave one Pokémon per Gym that your team controls. This bonus Stardust may be claimed at the shop using the shield icon in the top right of the main menu.
- Hatching a Pokémon: awards more Stardust and Pokémon Candy than catching the Pokémon in the wild would.
- Transferring a Pokémon to Professor Willow: awards a single Pokémon Candy for that evolutionary line.
- Evolving a Pokémon: awards a single Pokémon Candy for that evolutionary line. The game doesn't actually make any note of a Candy being received, but if you evolve a Pokémon, you'll always end up with an extra piece of Candy!
You can see how much Stardust and how many Pokémon Candies you have to spend on a specific Pokémon on its summary screen underneath its type, weight, and height specs. As with experience and evolving in the core games, at the end of the day, it doesn't matter whether you focus on powering up your Pokémon first or evolving it first. You will spend the same amount of Stardust and Pokémon Candies either way.
Once you've acquired some Stardust and Pokémon Candy, it's time for some training!
Powering up a Pokémon
Powering up a Pokémon is done from its summary screen and requires a combination of Stardust and Pokémon Candy.
A gray and white half-circle bar above or behind your Pokémon indicates how close it is to its current maximum Power Up potential. Your current Trainer level partially limits the maximum potential of your Pokémon, so if you reach the maximum at one point and gain another Trainer level later, you will be able to Power Up your Pokémon further.
The amount of Candy required starts off at one piece, but as your Pokémon's CP increases, the cost gradually increases, as well.
How much Stardust is needed varies between species. It also gradually increases as you continue to Power Up your Pokémon and its CP raises.
Evolving a Pokémon
Evolving a Pokémon is done from its summary screen and requires a specific amount of Pokémon Candy dependent on its species. Once you have obtained the necessary amount of Candy for your Pokémon's evolution, the Evolve button will be enabled.
Like in the core games, evolving a Pokémon is a guaranteed means of significantly increasing your Pokémon's CP and HP in one fell swoop. Evolving a Pokémon will also instantly heal it, restoring its HP to maximum. Your Pokémon will also (in most cases) forget its old moves and gain new moves.
Evolving your Pokémon can also be a good way to level up your Trainer, since evolving a Pokémon awards 500 XP, as well as an additional 500 XP if you have never seen that Pokémon before.