Was checking Souji's Pixiv account again to see if he'd uploaded anything new. Then I noticed he had a Twitpic account listed in his Pixiv profile. So I clicked it to see if there was anything there worth reading or seeing ... and I discovered that he posts a ton of rough sketches there that, for whatever reason, he chooses not to upload to his Pixiv account. Below are some of the particularly nice ones I found, but you can shop around for yourself
by clicking this link.
(While the game has been out for several months at this point, I guess I should warn,
BW2 spoilers inside, so don't click if you still haven't beaten the game's Story Mode and you care about plot spoilers.)
You can even see
his rough sketch of the Cynthia & Caitlin picture I shared a few weeks ago. Anyway, there's a lot of great stuff in there beyond what I included above -- pictures of champions, gym leaders, villains, you name it -- but like I encouraged, if you like what you see above, check out his Twitpic account yourself and shop around. Only a few of these works have Pixiv-account equivalents, but it's worth your time to double-check
his Pixiv library of works because anything he has on Pixiv is much,
much higher resolution than even the alleged "full size" versions of the pictures on Twitpic.