With Bitbucket you can configure the default reviewers that get added to pull requests on a repo and project basis. And after the pull request is created, other individuals can be added as “watchers” to the pull request (https://confluence.atlassian.com/display/STASH0311/Using+pull+requests+in+Stash#UsingpullrequestsinStash-Watchingandnotifications)
However, there is no way to configure a default set of watchers for the entire repo — who are not required to accept/decline every pull request, but receive notifications about every pull request.
Phabricator has a notion when creating a code review for two separate lists for the reviewers vs subscribers (the latter akin to stash’s “watchers”).
With stash, it woudl be extremely useful to specify a default set of watchers could be specified along the default set of reviewers for a project.