I know its holistic, but specifically whats needed.
Really vaguely put by UC admissions: “outstanding scholarly achievement” or something. Those who are accepted into Regents get accepted by the school around early February, but have to interview for Regents in the time between then and regular admissions decisions. Regents decisions come out when decisions for non-Regents kids come out. A friend of mine (ultimately MIT c/o 2019) got Regents from UCB (and I think UCD too). I don’t know much of his profile (GPA, test scores, etc.) but he did have some nice ECs.
UW GPA: presumably around 4.0
SAT: 2200+ for sure.
AP Scores: Chinese (5), Calc BC (5), Chem (5), LAC (4), took 3 more in senior year: AP Stats (5), Physics 1 (5), third test unknown, but definitely a 5 there too.
Major: Chemistry or Chemical Engineering (applied to CoC for Berk)
ECs:
President of Science Olympiad
Ran for the school
Won lots of awards from Science Olympiad (do not know which ones)
Top 20 Chem Olympiad x2
(summer) ultimately IChO competitor
Had a bunch of other stuff for chem.