Ok, I am 20 years old and unemployed with a credit score of 650. I need to get a used car loan of 7500 or maybe more. I have stocks worth 13k. And I will have an income of 400 every month from my brother. I bank with Wells Fargo.
Will banks such as Wells Fargo or Chase give me a used car auto loan? If so, how much do you think the interest percentage be? Does the bank even care if I have assets? or an income of $400 a month?

No they will not.
Without a job, you will not get a loan. You will need to get a cosigner, though I would not recommend this to you brother, or you will have to liquidate some of your stocks. You should also be looking at a cheaper car.
Auto finance is what I do for a living and sorry but without a job no lender is going to give you a loan unless you have collateral worth more then the loan amount that your willing to pledge, and even then you would have to deal with your own local bank.