While starting on Route 765, you will see that it is also connected to Route 756 and Route 757 which will take you directly to Molten Cave. Be careful. The area is pretty rugged and has a lot of rocks and mountains. Try not to use your bike or run. No one wants you to slip and fall, now do we? The weather is actually quite normal and has little rainfall. This is a good place to obtain some Pokemon. This area holds plenty of Geodudes, Sandslashs and Skarmory. You may even see a Smeargle, Houndhour and Snowlax as well.
Good luck on your journey, Pokemon Trainers.
Pokemon
-Geodude
-Sandslash
-Smeargle
-Skarmory
-Snorlax
-Houndhour