Laith Ayesh has a script for us:
In a few scenarios, you might need to scale multiple databases on a logical server (not part of elastic pool) at once, the azure portal only allows you to scale each database individually. This can be achieved using the following PowerShell script:
just modify the parameters like SubID, the resource group and server name and then pick the service tier you want and run the script:
Click through for the Powershell script and an important note.