I stopped with the first generation really. It's realistic that way (yeah, it's a fictional world and a cartoon but please hear me out) because there's no way that suddenly 250 more pokemon can be suddenly discovered. In the world of Pokemon, they would of came across the breeds altogether. It would be like if I had a show and everyone being in a civilized society soon discovered what 'birds' were all of a sudden in some other country. It doesn't make sense.. in fact what I said doesn't make as much sense as it should.
Point is, the first generation is the golden era, the classic. After that it was all because the demand for Pokemon was high, and they couldn't keep people amused with the 150 Pokemon they already got to know by heart. Yet, doing this often with 150 Pokemon breeds each time will put a huge strain on them. I mean, they already ran out of ideas due to making this a Pokemon:
.. Looks like, a duck that's blue. Not saying the games aren't enjoyable, but I fear Pokemon cannot last forever and might end soon. Maybe.