After Kusaka and Yamamoto won an Inkpot award at Comic-Con, they did an interview with some interesting tidbits
>http://www.cbr.com/pokemon-adventures-kusaka-yamamoto-gotta-draw-them-all/>CBR: How did you discover the personalities of the different Pokémon? Was it difficult to learn to write and draw so many characters, each with its own personality?>Hidenori Kusaka: In the first game, there were 151 [Pokémon]. It was one of the first series where everyone memorized all the characters and all their names. There are other games, for instance “Dragon Quest,” [where] even if you played the entire game, there are a lot of cases where 100 or so new monsters come out, but you don’t really memorize every single one. So as a phenomenon, it was amazing that everybody was memorizing all 151. I think they created something that was really easy for people to memorize. To get back to your original question, I think we were really helped by that easy-to-remember aspect that they created. But now they have made so many Pokémon — it’s a little different compared to the original.>Satoshi Yamamoto: To be completely honest with you, I haven’t memorized all of them. There are various series, and if we are talking about the series we are working on right now and the few Pokémon that are especially important in the plot, then I definitely do remember how to draw them, [but] when I’m done writing one series, it kind of goes in and out the other side. 