Oddly, I'd actually say "none". You don't need academic qualifications to be an expert in Atlassian stuff, I think experience, the ability to think, and the soft human skills like listening and then questioning people (your end users mainly) are far more important. I have chosen to hire people as consultants who have no Atlassian experience but were good at asking "why?" when people came to them with problems.
The Atlassian accreditations (passing the exams) are a good reference though - when writing the questions, we were told to aim them at people who had at least two years experience as an Atlassian admin.
