I am preparing to submit an app that records trails (like Runkeeper) to the app store, and I think that it would be great if the screenshots of my app shows it filled with trails on the main screen. But the problem is, it is very time consuming to record trails and save them in the iOS simulator, and heck, I've got to do this time-consuming task for every iPhone and iPad required. You may think that it is less time consuming if I recorded trails with real devices. But I don't have all the devices. So I've come up with a solution to use Photoshop to fill the main screen screenshot (only the main screen, only one screen) with content, but fake ones, but they look really real, and it's hard to differentiate between a real one and a fake one. But does App Store Review Board allow this? Thank you very much.
Only the App Store review staff can provide an absolute answer.
However, many apps in the store show modified screenshots. Providing mock content is common place when advertising document based applications.
Submit your app for review. If the review is rejected, they will provide a reason and you will have the opportunity to resubmit.