A typical initial venture capital pitch should be 10 minutes and should not go over. VCs generally have little patience and typically review many pitches.
The following elements should be included in the pitch (this list is adapted from the Southern California Biomedical Council (socalbio.org))
1) A opening that describes the problem and the potential solution
2) A description of the technology/product, how it improves the situation, how it is different from other approaches.
3) The business strategy and competitive landscape. How will your product penetrate the market and begin to make money?
4) The team of engineers, scientists, and business people involved
5) What's been accomplished to date
6) The next milestone and the resources needed to get there.
I would also add one slide that shows representative data demonstrating that you have done preliminary engineering or scientific work.
Keep in mind that the purpose of the "pitch" is to get in the front door. You can't "prove" your solution "works" in this pitch. Moreover, the VCs tend to be business people who will bring in consulting scientists and engineers to evaluate your product, should your 10 minute pitch be successful.
I would give the same advice as for a presentation to an academic audience, or in fact for any audience. "Script out" what you want to say prior to making slides and include only slides that tell that story.