The Format-Custom cmdlet is one way of displaying the content (properties) of an object.
The view is hierarchical and not in a flat list.
Unfortunately you can't "feed" the output into another cmdlet.
You will probably have better luck with the Select-Object cmdlet.
There you can specify on the Property parameter which properties shall be shown.
To find the available properties in an object, you can pipe the object to the Get-Member cmdlet.
Get-HVPool | Get-Member