The cover page for the official Black 2 and White 2 guidebook has confirmed the eight Gym Leaders of the games (in counterclockwise order): Drayden, Clay, Cheren, Elesa, Homika, Shizui, Burgh, and Skyla. You can just barely make them out in the bottom right corner of the page below. Out of the returning Gym Leaders, only Elesa has new artwork to reflect her dyed black hair and new outfit. It’s currently unknown what happened to Cilan, Chili, Cress, Lenora, and Iris, but they may appear in some capacity like Brycen, who is part of the Pokewood feature. Thanks goes to AAPF for uncovering the scan!
An additional scan of the guidebook’s type chart shows that Ghost-types aren’t resistant to Bug-type moves anymore. However, this is more than likely an error or misprint, as type effectiveness has never been changed during a generation and this could lead to compatibility issues when connecting to the older DS games. We’ll find out if this is true or not when Black 2 and White 2 are released next Saturday, so be sure to check back!