>>53353280I made a post about that in another thread. Here it is:
>>53338870At the start of the anime, I think Ash is supposed to be shorter than average for his age. While Misty on average is a bit taller(and slightly curvier) than most 10-year-old girls. Mallow in this series being another example of an early growth spurt.
However it seems Ash did shoot up a little at some point, because now he's almost the same height as Misty. I don't believe that's an oversight.
They're both still a good bit shorter than Brock who himself is still noticeably shorter than some adults, aside from the shorter ladies(Nurse Joy for example). So they're all pretty small still.