#646 - Lengthy Story

According to GameFreak scenario writer Toshinobu Matsumiya, the story and characters of Pokémon Black and White took over a year and a half to create. Also, he began writing the story short after Pokémon Platinum was released.

SOURCE: https://web.archive.org/web/20101017132608/http://www.gamefreak.co.jp/blog/staff/?p=202