How to beat team galactic in pokemon diamond for ds?

I am having trouble beating team galactic in mt coronet. I almost got to the top but one of the galactic people are in the way of the opening to the next part of the mountain. he sais he doesnt have any pokemon, so I cant battle him. I am wondering if I am in the wright place and how to get rid of the person.
also I want to know how to get into sunnyshore city. some guy wont letme through because of a black out.

Hi,

You're going the wrong way, that grunt stays there. find a different way up and you will lead into a snowy place, its hard to find but there is a spot which gets you higher into the summit, you're going in the right direction though, just don't mind the grunt.