Junichi Masuda has explained why Pokemon's core gameplay hasn't changed a great deal since the series started with Pokemon Red and Blue back in 1999.
The Game Freak director compared Pokemon to sport, arguing that the game doesn't need to change too much to be enjoyable.
"Finding that balance every time is very difficult," Masuda admitted in an interview with Gamasutra. "But when you think about games, just like playing, for example, soccer and basketball, they're games that have been around for a very long time. The core gameplay of those - the core of how you play basketball and soccer - hasn't really changed. Over the years, there's regulation changes or rule changes to those games, but the core gameplay doesn't really change for those, and that's how we kind of feel about Pokemon as well."
He's got a point but we'd argue that Pokemon has changed over the years. Go back and play Pokemon Red or Pokemon Blue now and then play Pokemon Black or White to see how the series has evolved. You may still have to beat gym leaders on your way to defeating the Elite Four and becoming the Pokemon champion but it's wrong to say that the series hasn't moved on.