The "evolution" that a single pokemon undergoes is more like a metamorphosis. True evolution exists in the pokemon world as well. In fact, pokemon and humans share a common ancestor. Now there are some backwards religious types in the pokemon world that will tell you Arceus created the world and the legendary dogs sacrificed themselves and were then reborn into their current forms and some other stuff, but that's bs.
im guessing were pretty much finished with evolution. if anything, it will be like in Wall-E where we start breaking down. evolution occurs to help an animal adapt to its environment, but now humans pretty much just change our environment instead of our body.
plus the way evolution works is that random anomalies turn out to be beneficial, so the host doesnt die, so the host passes the genes containing the anomaly onto its offspring. now whenever a child is born with an extra set of pinkies we chop them off, and if they have hyperactive brain functions we feed them adderall for breakfast.
The only way for a population/species to stop evolving is if it goes extinct. Evolution doesn't help animals adapt to their environment. Evolution has no purpose. It doesn't necessarily lead to an increase in complexity or survival. Natural selection, and thus adaptation and evolution, is essentially a random byproduct of cell replication. Also, environment is not the only pressure that determines the "success" of mutations. Mate selection is huge. Due to our cognitive abilities, we humans can drastically alter our perceptions of what is desirable in a mate in less than a generation, resulting in a brand new suite of genes being selected for, spurring on evolution. In summary, sex up girls with nice shoulder blades, because I want our descendants to fly goddommit.
More humans means more chances for mutation. Also, people don't have to die for natural selection to occur. "Better" genes take the place of "lesser" genes every time a child is conceived. Some people will have children, others won't. The contents of the gene pool are constantly being shook up.