You could do something like this
Get-VMHost | Select Name
, @{N='ScratchPartitionSizeGB';E={
$esxcli = Get-EsxCli -VMHost $_ -V2
$scratchPartition = Get-AdvancedSetting -Entity $_ -Name ScratchConfig.ConfiguredScratchLocation
$fs = $esxcli.storage.filesystem.list.Invoke() | where{$_.MountPoint -eq $scratchPartition.Value}
$fs.Size/1GB}}