Hi Hector,
It depends on your discretion that what all masters/SubMasters you will be using in Intercompany trade in your environment.
So, for document cycle, it will be mandatory to maintain identical records for masters like Vendor group, Payment terms, currency etc. However, if you want to use UOM Group based Item in document cycle, then records need to be maintained for UOM group master also.
As a thumbrule, you need to maintain identical records for all the Intercompany relevant masters/sub masters that you will be using in your Intercompany environment.
As your query is quite open ended and could have multiple implications depending upon business cases. I would suggest you to get in touch with SAP LPE in your region, to ensure keymapping process sanctity.
Regards,
Agneesh Jain
SAP Intercompany Team