how do i get to the volcano

Some of the people were right. You have to the National Pokedex to go to Stark Mountain. But I do suggest that you have some Pokemon over level 50 or 60 because the Pokemon there are in that range. Good luck. Lt. Shadow Verwolf out.

Well, you do need the National Pokedex in order to get to Stark Mountain, but you don't actually need Pokemon at Level 50 to get to Stark Mountain, it's just most Pokemon getting there and in Stark Mountain are at a Level 50 or Higher.

To obtain the National Pokedex; You must see all the Pokemon in Sinnoh, then show your pokedex to Professor Rowan, then you will receive the National Pokedex from Professor Oak.

Also, here are directions to get up the Moutain to the Entrance:

Go past 207, to were ash starts falling from the sky.

* To Jump the Rocks, Remember to have some distance, to Pick-Up more Speed *

1. Jump the First Rock by using your Bicycle in High Speed
2. Jump the Second Rock by using your Bicycle in High Speed
3. Go down and hop over the log
4. Go left, up, right, then up the steps
5. Go right, and go over the rail with you Bicycle
6. Get off the rail, and head up, go into the grass, and head up
7. Get out of the Grass, and turn right, and hop over the two logs
8. Go right, and through the small patch of grass, and up the 2 set of steps
9. Head up through the patch of grass about half way, then turn left, and head through the patch of grass
10. When you get out of the patch of grass, the entrance to Stark Mountain will be insight

Hope this helps you!!!

Yes, you do need to National Dex to get to Stark Mountain. Although your Pokemon don't need to be over level 50, I would suggest they should be, as the Pokemon there are around that level, if I remember correctly.

Hope this helps,
~Lukie.