Everything has been said, but I'd like to input.
I am 15, so is my Girlfriend and we both love Pokemon. We recently watched the entire first season, and we are forever fighting over my DS. I don't think I will ever 'outgrow' Pokemon, and this entire concept of childish video games is laughable.
My favourite joke about people who play only M rated games. *sarcastic voice* 'This game is rated M for Mature because it contains Violence and Swearing, and Violence and Swearing are signs of Maturity.'
And as for your friends, to be honest, someone who thinks and openly says these things to you isn't worth being friends with, but only if you feel that they absolutely mean what they say, and aren't just teasing :3
I used to have friends like that, and I decided I would rather have no friends, then to endure them, or to pretend not to like something I love. It took me a long time to find my place in school, most of my peers are very unpleasant people, and being as... lets say 'individual' as I am made things harder. The friends I have now are great, and most of them like Pokemon too.
If you have a single friend with similar interests to you, I recommend spending more time with this person, than a group of people who don't truly accept you.