Pokemon evolve at a certain level in Pokemon game. So you got to let them fight so your pokemon can evolve, look different, learn news move and become stronger. Some pokemon like growlite need a evolution stone like fire stone to evolve or else it will stay the same no matter what level it is, but it will still learn news and get stronger. And some pokemon you have to trade them with other in oder to evolve them. Some people may like there pokemon how they are right now. So they don't want to evolve them. This also happen in pokemon anime and movie.
Pokemon or creature, based on various plant, animals, and other concepts, inhabit virtually every corner of ther world. Many pokemon made their homes in forests and other habitat streching acros the various regions of pokemon land. Pokemon that are own and catch by people are kept in poke balls, and it allow them to be quickly sent into battle or to perform a task and made them sade, and easier to transport because some pokemon can weight thousand of pound and they are hugemous. Pokemon beging their lives by hatching from from egg and many of them will evolve to grow stronger and larger.
