Nah, in Pokémon GO to power up (level up) your Pokémon and to evolve them you need to get Candy of that specific Pokémon. In this case Turtwig Candy. The two main sources to get Candy for a Pokémon are by catching them or hatching them from eggs. There are a few other ways too, but reward less Candy. So it's actually necessary to catch a lot of the same Pokémon to make them stronger :D