Hi Anjani,
Relationship should be established between Supervisor and Employee for approval process. As you mentioned that while submitting a timesheet, the status is seen as 20 in CATSDB and when you verify via SWIA, the request shown as pending with the Manager which gets updated in the Ztable. So here you can put a check on status "Pending" in BADI and call Send out Notification mail to the respective Manager, in this way manager will get the notification in his inbox whenever employee submit his timesheets... Hope this help...