Got all 121 main stars with my friends in one night with SM64EX Co-op. What an experience. As a casual who's only beaten 64 once this difficulty is really something else, it put all my Mario 64 movement knowledge to the test with some of the craziest platforming challenges I've ever seen. Would never have been able to 100% without my friends there, the later levels get extremely demanding with constant difficult platforming. While nowhere near kaizo requirements you definitely need to be prepared for a challenge greater than the original 64.