Series 6 is the FINRA exam for persons who will be selling only mutual funds and variable annuities. Series 63 is the FINRA exam to sell stocks, bonds, warrants, and such.
If you really want to do financial planning, check carefully. With just these exams, there is a good chance you'll be a commission based salesman in fact if not in name.
Series 65 is the FINRA exam to operate as an Investment Advisor representative. It's the one that covers goodies like the Prudent Person Rule, risk tolerance, and other things that I'd expect an actual investment advisor/financial planner to know about.