I'm pretty sure I'm not the only one asking this question.
Since Generation One, Ash Ketchum, the show's ever popular hero, has yet to age into a teenager. I mean, come on; he still looks like a ten year old with his get-up. A lot of Pokemon fans have pointed that out and have come with numerous theories about why Ash Ketchum hasn't aged one bit since he started his quest to catch 'em all.
But in the games, Ash is replaced with Red, a young boy who looks exactly like him but sports a red cap and uniform. He too has the looks of a ten year old, despite being the oldest protagonist in a Pokemon game!
According to Bulbapedia, Ash Ketchum started his journey at a tender age of 10. According to the original Japanese television show, Ash started his Pokemon journey at 12 years old. This was in 1998 and now that it's 2013. If you calculate all that, he should have been around his 20's already. However, he has aged so little, which prompted a lot of fans to question that aspect of his life. Some are saying that it's the producers who made the decision to keep Ash young, since this is a children's show. Others are saying that the days and months in the Pokemon world are slower compared to here in the real world. Others are saying that he has a Pokemon shirt that he keeps wearing in secret and it has mystical powers that keeps him young during the 800+ episodes.
Well, no matter how ridiculous these theories are, some of them actually makes sense. One popular theory was that the whole events in the Pokemon anime was just the hallucination of a comatosed child. The article was so well-explained that a lot of fans actually complained, stating that it was "so disturbing." I went online to find such a particular article and the author did explain that it wasn't going to be a pleasant article, so I guess those who complained did not heed to the author's words.
But I have to admit, the way the author explained everything, it was kinda creepy and dark. Most people consider the piece as mere fanfiction. I do too.
The sensible explanation was that the world of Pokemon had a very different time zone. I wouldn't be surprised; it is a work of fiction after all. It doesn't take a rocket genius to figure that out. In actual sense, the director of the anime show confirmed that the Pokemon anime was supposed to last for only a year and a half; however, because of its popularity, they realized that they had to continue the whole series. And now, the show already has 806 main series episodes, 16 movies and a number of different side-stories but still related to Pokemon. Not to mention the Pokemon t-shirts, toys, trading card games and the whole merchandise that started because of the show's popularity!
To be honest, I really don't mind if Ash never grows up. Because I know that the children of today and in the near future will come to love him and the different species of Pokemon just how I used to see him during my childhood days.