(Before you read, I am relatively new to this, so forgive me if I use any terms/phrases wrong.)
So I have just beaten the Elite Four on White 2, and I want to start getting more involved in battling competitively. I have been researching endlessly on this topic, and one thing that has sort of confused me is involving natures and movesets. I know what natures there are and what they do, but my problem is picking a moveset based on the nature of the Pokemon you have. For example, I want to turn my Aerodactyl into a physical sweeper, because it has a great speed and attack stat. A recommended nature I have researched for this role would be Jolly, which increases speed while reducing special attack. However, my Aerodactyl has an Impish nature, so it's defense gets raised while it's special attack is lowered. Because of its nature, do I have to base the moves more around defense, or can I go ahead and continue with the physical sweeper role? And if I have to base moves around the Pokemon's current nature, how would I go about doing this?
TLDR; Do I base moves around Pokemon's current nature, or can I pick whatever I feel like?