
Here's a flow chart on restarting play off a dead disc/stoppage (I just pasted it into Gemini and such), based off of
https://usaultimate.org/rules/#10.D
Self-checks, ask the other team if they're ready, first
Everyone goes back like what Anthony says
This includes injuries. It's not always the injury substitution player who checks to restart play, which people tend to implement wrong.
If someone has the disc and defense has to sub out, the marker (or thrower) still checks it in, like above.
If it's a turn, and the new offense has to sub a player out, it's still a defensive check to restart play.