Pokemon GO gives you the option to Level Up your Pokemon whether it is a starter or one you find searching your surroundings. The three basic starter Pokemons are comparatively more difficult to Level Up to those you get later. This is obvious as the starter Pokemons have very powerful evolved forms as compared to others.
For an instance, Charmaleon and ultimately Charizard ( evolved from Charmander ) are more powerful than other fire type Pokemons as we know from the anime. So we suggest you to focus on other Pokemons instead of Charmander, Squirtle and Bulbasaur at first.
How to Level Up a Pokemon
There two different items available that can be used to Level Up a Pokemon – Stardust and Candy.
Stardust can be used to both Power Up and Evolve a Pokemon. So you need to keep a good stock of it. Candy on the other hand, is based on specifically on the Pokemon. So that means Bulbasaur will have Bulbasaur Candy, Squirtle would have Squirtle Candy and likewise.
You can use your Pokedex to Power Up or Evolve a Pokemon.
Candies can prove to be a bit tough to get. But there’s a way in which you can farm the type of Pokemon you want to Level Up. One you get enough of them, you can Transfer them which will get you those Candies. Note that transferring a Pokemon means losing it forever so you better think twice before doing so.
You can find the complete Pokemon GO Wiki Guide here.