reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Communications /v ConfigureChatAutoInstall /t REG_DWORD /d 0 /f This ought to prevent the auto installation of Teams. NOTE: You'll need to take ownership of the "Communications" registry key first and grant yourself the relevant permissions prior to adding the above value.
Via the Windows ADK System Image Manager, in the following section: Microsoft-Windows-Shell-Setup | Microsoft Docs (docs.microsoft .com/en-us/windows-hardware/customize/desktop/unattend/microsoft-windows-shell-setup) - The web docs appear to be missing the actual entry, but it's available via the software. I had noticed that many of the settings available within the System Image Manager for use in an unattend/autounattend.xml answer file are actually the names of registry values and so I just searched for that particular entry in the registry following a virtual machine installation(With an autounattend.xml containing an entry with that setting) and found it, I tested it on a live machine afterwards and it appears to be working so far. Here's the setting from the answer file: Spoiler: unattend.xml