https://wccftech.com/marvels-avengers-co-op-gameplay/

One of the most persistent questions surrounding Marvel’s Avengers since it was announced has been “How exactly does co-op work?” Avengers developer Crystal Dynamics has said that co-op will be relegated to special missions apart from the main single-player campaign, and that players will be able to freely assemble teams of up to four from the game’s roster of characters. Beyond that, we haven’t shown how co-op will actually work in action.

Thankfully, Crystal Dynamics finally provided a look at co-op during the just-completed Marvel's Avengers War Table livestream, which just wrapped up. And that’s not all! They gave us a taste of a new single-player Thor mission, featuring Hulk and Iron-Man as wingmen, and detailed the game’s character customization. If you’ve got about half an hour, you can check it out for yourself, below.