In apost on thePokemon Goofficial websiteFriday, development team Niantic Labs revealed the new Buddy System.
Previously, Candy was only obtained through catching Pokemon, making rarer Pokemon harder to power-up.
Included screenshots reveal examples of a trainer using Charmander, Snorlax, and Squirtle.

Credit: Pokémon
This chosen creature can also be changed at any time in the players profile.
See the screenshots of the new system below.

Pokémon