user/visitor generated content and display

We want to run competitions on our site where we post a “challenge” (custom post type) and subscribers submit “solutions“ (another cpt). The solutions will have an image (featured img), body and a few custom fields. Each solution will be linked to one challenge and we will list solutions on the website so visitors can vote-up/like/follow them. Can you suggest a combination of your plugins that would allow us to do this?

cheers - Tansel