oyu fly over it with a dragon type pokemon
there are a lot of trainers who want to battle you there, and some Pokemon that you probably cannot see at any other places in the unova region.
first cross the drawbridge at route 5. then find team plasma in the bottom left warehouse of cold storage. next challenge the gymleader and win a mine badge. tho enter chargestone cave, leave the...
Keep going down. But search chargestone cave walkthrough on youtube.
you get out the charge stone after beating N