I've only ever been on teams that do "pre-merge" review. This is the standard "here are my changes, let's get them approved and merged."

I've only heard of "post-merge" review and would like to hear more about it from people who've worked on teams that do that. It seems like everyone on the team needs to be a high-performance coder in order to do that? What are the pros/cons compared to "pre-merge"?