Hi guys! I got into UCSD Sixth college and I will be a freshman next year. I would love to get an apartment with my friend who will be in Roosevelt college. Is this possible?
No.
You can only request a roommate if you are both in the same college.
http://hdh.ucsd.edu/LOC/faq.asp
There used to be an option for all campus housing (for continuing students, not incoming freshman), where students from different colleges could life together. But it looks like it wasn’t offered for the most recent housing selection so they may have discontinued it. They may bring it back in a future year.
http://hdh.ucsd.edu/roomselection/
You could live off campus, if you really want to live with your friend. But it’s easier to just live in your own colleges.