A Pokémon evolves from its details window once it meets the condition: a level, or an evolution item such as a Fire Stone or a Moon Stone. Each Pokémon's Pokédex page says what it needs.
- An evolved Pokémon is always stronger than the form it came from.
- It keeps its level, genes, stars, traits and held item, and the moves it learned when its new form can use them.
- An Ancient Stone stands in for any evolution item.
- Some Pokémon can evolve into more than one species (Gloom into Vileplume or Bellossom): you choose.
Evolution items
Common type stones (Fire, Water, Thunder, Leaf...) drop from defeated Pokémon of their types. Rare evolution items (Moon, Sun, Dawn, Dusk and Shiny Stones, Metal Coat, King's Rock, Dragon Scale, Up-Grade) drop much less often and are sold at the Poké Mart for ribbons. See Items.
Evolving a shiny
A shiny evolves into its evolution's shiny, which is rarer. So a shiny also needs Glimmer Stones: one for each time the next form's shine is twice as rare. See Shinies.
Nightmare forms
A Pokémon Awakened into its Nightmare form doesn't evolve any more: evolve it first. See the Nightmare World.