An Ivysaur evolving into a Venusaur in Pokémon Black and White.

Evolution is the process by which a Pokémon metamorphosizes, or evolves, into its next form.  There are various ways a Pokémon can evolve, the most common of these being by level.

Aside from changing the Pokémon's physical form, Evolution usually increases the Pokémon's base stats, and can alter its Types, Abilities, and even moves.  However, Natures, EVs, and Shininess are preserved upon Evolution.
Pokémon Evolution

Pokémon Evolution

Pokémon Evolution, credit to LQLINK2630.

Evolution FamiliesEdit

By definition, an evolution family is any group of Pokémon that are directly linked by Evolution.  More clearly, the Basic or Baby Pokémon and all of its potential Evolutions are considered a single Evolution family.  All eggs hatched from an evolutionary family will yield the same Pokémon.

Stages of EvolutionEdit

Two-Evolution FamiliesEdit

Not to be confused with a family with two stages, a Two-Evolution family is the most standard kind of Evolution.  It is an Evolution family where the basic Pokémon evolves from its basic form twice.  All starter Pokémon are members of Two-Evolution families.  Some examples are Froakie, Dratini, Caterpie, and Lochro.

One-Evolution FamiliesEdit

Not to be confused with Pokémon that do not evolve, a One-Evolution family is a family where the basic Pokémon evolves only once.  It is disputable whether Fossil Pokémon can be considered part of the One-Evolution family, because the Fossil itself may be considered an Evolutionary Stage.  Some examples of One-Evolution Families are Ratatta, Inkay, Larvesta, and Tazman.

Non-Evolving PokémonEdit

Non-Evolving Pokémon are Pokémon that remain in their most basic form forever.  All legendary Pokémon are Non-Evolving Pokémon.

Branch EvolutionsEdit

Branch-Evolving Pokémon can evolve into multiple Pokémon, depending on its method of Evolution.  Some examples are Poliwag, Eevee, and Ralts.

Methods of EvolutionEdit

Aside from just meeting a certain level, Pokémon can evolve in various ways.  They include:

  • leveling up with high Frienship
  • leveling up with high Affection
  • leveling up while holding a specific item
  • leveling up while knowing a specific move
  • leveling up in a specific location
  • trading the Pokémon
  • trading the Pokémon while holding a specific item
  • trading the Pokémon with a specific Pokémon
  • using a specific evolutionary stone on it
  • leveling up the Pokémon with a specific Pokémon in the party
  • any of these, when the Pokémon is a certain gender
  • holding the system upside-down while leveling up (upon a specific level)