Unfortunately, I've known people who are convinced that they are. Bizzare. But of course, no, I don't think they're real. And if they were, what a headache it could be! Pokemon is a nightmare mishmash of contradictions, and there are a lot of things about them that don't make sense. 10ft Water dragons such as Gyrados obeying 10 year olds? Alakazams with an IQ of 5,000 not being the dominant species? Darwin would surely be spinning in his grave.
Sure, if you had some easy way of explaining it all, Pokemon being real would be neat. But since that's impossible, it would cause a right kerfurfle for the fabric of reality.