For the creatures of the Pokémon games, evolution is a part of life, but some species look better before they evolve. There are many cool, cute, or otherwise good-looking Pokémon whose later evolutions aren't as good as their earlier forms, especially with eight generations of games released and counting. The upcoming PokémonScarlet and Violet will be Generation 9, and its Pokémon will hopefully have better evolutions than those of games past.
In Pokémon, evolution is the process by which Pokémon attain new, more powerful forms. The conditions needed vary from species to species; while most simply require battle experience, others need a bond with their Trainer or a special item such as an evolutionary crystal, and some Pokémon evolve when traded to another Trainer. When Pokémon evolve, they typically grow in size and take on a new appearance, sometimes changing quite drastically. They can even gain new Types, and it's not just their biology that can change; some Pokémon can have an entirely personality after they evolve, though this is more prevalent in the anime than the games. The majority of evolutions are an improvement on appearance and battle capability, but there are Pokémon that are better off not evolving.
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Almost every player has that one Pokémon they put an Everstone on no matter how much better they would be in battles. Sadly, most need to evolve in order to be viable, especially in the later stages of the games. The Pokémon anime repeatedly sends the message that evolution isn't necessary — with the most famous example being Ash's Pikachu, who has taken on immensely powerful foes without ever evolving into Raichu, arguably a much cooler Pokémon —
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