Does Preventing a Pokemon from Evolving?

Stopping a Pokémon from evolving is quite easy. You can attach an Everstone item to your Pokémon, which will stop it from evolving as long as it's equipped. The other method involves spamming the B button every time your Pokémon goes to evolve and the cutscene begins to play.

What happens if you prevent a Pokémon from evolving?

Yes, even if you decide to stop an evolution you can change your mind and have that Pokémon evolve later on. That's because the Pokémon will try to evolve again the next time it levels up.

Is it better to stop your Pokémon from evolving?

The advantage of stopping an evolution is that Pokemon can learn moves at a lower level than when evolved. After evolving, Pokemon will often learn the same move at a higher level, or in some cases, they will lose the potential to learn the move at all.