As a test, I looked at the websites of two partner airlines.

First I checked Deutsche Lufthansa. I wanted a one-way ticket for flight LH6227 (LH codeshare for SK635) from ARN to FRA on the 10th of January. I'm offered "Business Saver" and "Business Flex".

Then I checked United Airlines. On the 9th of January, SK525 ARN-LHR followed by UA17 LHR-EWR, then on the 16th UA70 EWR-AMS followed by UA7051 (codeshare for SK556) AMS-ARN. UA presents SAS Plus as business class, both for the codeshare and for the SK code.