For Replication Subscriptions, we use sp_replmonitorhelpsubscription
https://msdn.microsoft.com/en-us/library/ms188073.aspx
For the status from Replication Agents and Replication Publications we select the run_status FROM msdb..sysjobhistory joined with msdb..sysjobs on job_id.
This is a table with all available status and severity definition
| Status | Severity |
|---|---|
| Started | Normal |
| Succeeded | Normal |
| In progress | Normal |
| Idle | Normal |
| Completed | Normal |
| Running | Normal |
| Not Started | Normal |
| Retrying | Warning |
| Failed | Critical |