Undergraduate

Freshman
You need to take SAT I and SAT II (2 subjects related to your major).
Unless you have studied in an English-speaking country for more than 4 years or have scored more than 670 (please confirm with university) in SAT I critical reading, you will need to take IELTS or TOEFL.
A high school diploma is needed as well.

The application is very simple and is shared between 10 UCs. The application fee is $70 for local applicants and $80 for international applicant for each UC. Depending on how many UCs you applied to, the application fees can add up to a lot. Usually, most people will apply to 4 or 5 UCs with some being safety school.

You will need to complete 2 personal statements (essays). Try to be as honest as possible and be creative. Forget about what your teacher taught in school regarding scoring A1 or A+ in any English examination, the content in your statement should be genuine and true. There was one guy who got into UC Berkeley with his essay titled "Pencil". Some wrote about how he/she hates the family or what crime was committed. Be honest, can't stress this more.

Else, the application process is perhaps the simplest among all universities. Make sure you send the university the SAT and TOEFL score by the dateline and follow all the instructions given.

Transfer
Transfer student might find themselves easier to enter UCLA. As long as you fulfill the requirements you should be good. Talk to your community college counselor. The authors here are not transfers unfortunately.