If you want to add the Power Saver shortcut on your home screen that also displays the battery percentage, you must use your ZenFone's default theme. This shortcut allows you to switch between battery modes in an instant.
To add the Power Saver shortcut:
Launch Mobile Manager.
Tap > Settings.
From the Settings screen, tap Create Power Saver shortcut.
Go back to the home screen to see the Power Saver shortcut.