Using Virtual Partner
The Virtual Partner® feature is a training tool designed to help you meet your goals. You can set a pace for the Virtual Partner and race against it.

NOTE: This feature is not available for all activities.
From the watch face, select START.
Select an activity.
Hold Menu symbol.
Select the activity settings.
Select Data Screens > Add New > Virtual Partner.
Enter a pace or speed value.
Start your activity (Starting an Activity).
Select UP or DOWN to scroll to the Virtual Partner screen and see who is leading.

Virtual partner data

http://download.garmin.com/tw/download/manuals/forerunner935_TW_0A.pdf

https://www8.garmin.com/manuals/webhelp/forerunner935/EN-US/Forerunner_935_OM_EN-US.pdf