I attended a Buzz try out years ago (I did not try out to be Buzz, a friend did and I was in his skit). The requirements are mostly about being able to complete gymnastics moves while wearing the uniform with one portion related to showing the "buzz personality" via skit that you make up. As such, the people who tried out were former gymnasts, which were primarily women and short men.
He told me it was a 50% scholarship for being Buzz, so it was pretty competitive (he did not make it - was chosen as an alternate in case someone else dropped out, which didn't happen). IIRC, they selected 3 Buzz's with one being the main Buzz (football games).