First I should state that I enjoy the Pokemon franchise and have played some of it's games over the years, from Red/Blue, to Yellow, to Gold/Silver, to the remake of Gold (Goldheart) but today I came to an interesting conclusion: Pokemon is no difference then Call of Duty, where it releases essentially the same game.
Well you see Pokemon comes out with a new game every couple of years, adding more Pokemon, each iteration they are lazier at it. Add a few game mechanics and more or less progress in the same 'linear' storyline. Every so often they release an enhanced/remastered version of some of their original/older titles onto a new platform.
A few things that are always the same as well, only 4 moves (limitation originally for the Gameboy and Gameboy Colour) yet the DS, 3DS, etc have been able to handle a lot more than that. There is ALWAYS a version of team rocket who you have to stop from stealing everyone's pokemon, 8 gyms for that 'starting country/continent' and finally there is always an elite 4 to beat.