Individual species can evolve over the years as far as Pokemon are concerned, as well. However that sort of evolution isn't really what someone thinks of upon hearing the phrase 'Pokemon Evolution.' Pokemon Evolution is usually something that happens at a certain level, or with trading, or with evolutionary stones, or something of that nature. Change over time is something akin to how Magikarp as a species used to be rather strong, but grew weaker into what it's known as now. [a floppy red fish. :(]