So there are a couple of ways to do this. This first is to run this:
Select Caption from Nodes N
Join APM_AlertsAndReportsData A on N.NodeID = A.NodeId
Where N.NodeID NOT IN (Select NodeID from APM_AlertsAndReportsData Where ApplicationName = 'Name of your template)')
And Vendor = 'Windows'
Just replace the Name of your template with the name and run it for each of your core templates. Now, if these templates happen to be the only ones you've assigned your Windows servers you could also just get away with:
Select Caption from Nodes N
Join APM_AlertsAndReportsData A on N.NodeID = A.NodeId
Where N.NodeID NOT IN (Select NodeID from APM_AlertsAndReportsData)
And Vendor = 'Windows'
Which will list our all servers that have 0 templates assigned to them.