The worker in the passageway to Route 10 will stop you and say there is a big storm on Route 7. This is the event that unlocks Tornadus in Black and Thundurus in White. All you have to do is go to the house east of the Celestial Tower on Route 7. An old woman will pull you inside and give you soup while talking about the legendary Pokemon. Walk outside and your version's legendary roaming Pokemon will swoop down and the storm will subside. The storm will come back and it will fly away. From now on, it is in the south during the morning and the north during the evening.
Back at the start of Route 10, you will find a Battle Girl.
Cheren heals your Pokemon once you defeat him. Bianca gives you some Max Revives. Follow the path through the dark grass to the north. Two of the item balls you find in the dark grass are Amoongus, the evolution of Foongus. The two western balls contain a Hyper Potion and a Dawn Stone. There is a Black Belt looking for a battle in this grass.
Talk to the male Veteran on the south side of the bridge to receive a Dusk Stone. Walk east alongside the river to find TM 05 Roar. It makes your opponent's active Pokemon switch out. It will also end wild Pokemon battles. Hop down the ledge and go east to where you battled Cheren earlier. Continue east to the patch of grass to pick up a Full Restore. It heals any status effect and all HP. Battle the female Ace Trainer.
The old stone building to the north is the Badge Check Gate. There are 8 gates that you must go through. The key to each gate is one of the 8 Unova Gym Badges. Walk through each gate to get to Victory Road.