1) Do NOT put a bunch of screenshots of your app into the slides and talk about those. For anything like that, just show us the live demo.
2) DO have one "title slide" to introduce your team/project. (brief)
3) DO use several slides to provide some helpful visuals while you talk about your development process, software design decisions you made. In particular, I expect a UML diagram (not a complete one with all the methods and fields, but instead include a box for each of your classes, and show the key relationships between those classes.) The idea is to explain a bit about your software architecture at a higher level than raw Java code.
3) Maybe also one slide for brief reflection on teamwork/lessons learned?
Overall, I don't expect a large number of slides in the presentation, since much of the time will be spent on the interactive demo.