What to do about my boyfriend's needy guy friend?

You pretty much need to suck it up and get over it. I tried to come between my boyfriend and his best friend once, and it doesnt work. Chances are, if this is your boyfriends best friend, then he probably loves hanging out with him, and just has to agree with you when you complain about him. If you want to be with your boyfriend you have to accept his friends because truth is if he has to choose between the two, he will choose his friend. Friends are the most important relationship. You need to accept him.