Running multiple Linux Hyper-V hosts on Windows Server 2016 Standard

• Core-based licensing requires all physical cores in the server to be licensed. Servers are licensed based on the number of processor cores in the physical server.
•  minimum of 8 core licenses is required for each physical processor and a minimum of 16 core licenses is required for each server.
• Core licenses are sold in packs of two.
• Standard Edition provides rights for up to 2 Operating System Environments or Windows Servers containers with Hyper-V isolation when all physical cores in the server are licensed.
• For each additional 1 or 2 VMs, all the physical cores in the server must be licensed again.
• http://download.microsoft.com/download/7/2/9/7290EA05-DC56-4BED-9400-138C5701F174/WS2016LicensingDatasheet.pdf

Microsoft licensing would not cover non-windows guests. You should refer to their end user licensing agreement for details.