You may not have worded this question in quite the right way. Of course ... minors CAN do lots of things without their parents' consent; and I'm not aware of any law that requires THEM to obtain parental consent for anything. The laws have to do with 3rd parties' interactions with minors.
So, yes, a minor can seek legal advice ... the question is "will he receive it?"
If a lawyer gives legal advice to a minor, he probably shouldn't expect to get paid for it.
Please note that this answer does not constitute legal advice, and should not be relied on, as each situation is fact specific, and it is not possible to evaluate a legal problem without a comprehensive consultation and review of all the facts and court pleadings filed in the case. This answer does not create an attorney-client relationship.
Yes; however, minors may have an issue contracting for legal advice. Some minors are "emancipated" thus with the rights and responsibilities of adults.