Many times I am asked about who to put together a pitch for an animated show, this question can be difficult for me to answer because I have steadily weaseled my way in to animation over 21 years. And frankly I don't really know! What a pitch consists of changes over time, and since I'm not a writer what I put together for a pitch is very different from someone who is a writer creator.
All that said here is a link to a video from the CTN Expo (Creative Talent Networks) a talk by Heather Kenyon about how to create a pitch bible. This is the best instructional talk I have ever seen about creating a pitch bible, for all beginners and professionals alike. My one little piece of advice that I tell anyone who wants to tell me their amazing animated show idea; "Write It Down." The more you talk about something the more diluted it becomes. The exercise of sitting and writing is also good training for harnessing your creativity.
Watch and absorb.