Screenshot: Google
YouTube teased this last year but is now bringing the feature to creators. The new Go Live Together allows you to co-host live streams. Anyone with over 50 subscribers can invite a guest to host a live stream with them from an iOS or Android phone. The host can only invite one guest at a time, but they can swap in new guests during the same stream.
You can schedule these live streams through the desktop app, but you can only use mobile devices during the stream. Guests don't need to meet a minimum number of followers to be a guest, but the host will be responsible for guests violating any community guidelines. Hosts can earn revenue for ads in pre-, mid-, or post-roll form.