Why is Ash Ketchum still a 10 year old?

[Esmoreit]

Wetcoaster said:

Bursche said:
Why is it that Professor Oak had no idea that there were more than 250 original Pokemon? Did he not know that there was an outside world? The whole show is stupid after the first seaon.

YEAH! Isn't he the AUTHORITY on Pokemon? You're slipping, Oak, you're slipping.

and it was 150... 151 counting Mew.

 

 

Wasn't it so that Mewtwo was just a gen-copy from mew? As mewtwo should not really exist 150 seems reasonable.