Thank you. I'll find bigger images then.
@Dekken: That thought has crossed my mind, so I might set up a few wiki tasks like that at some point. If you want some criteria to go by in the mean time, I'd recommend making portraits for characters from the newest anime series and working backwards.
Finally found a good image for Dawn from the current Pokémon series:
@takashichea: Every image helps. By the way, don't forget to add the images to a "Profile Portraits" gallery on each character page.
@shels: That last image is pretty good but the other three could be better, but if they were the best images you could find then that's okay.