Bianca is in Professor Juniper's Lab, and you can battle her on weekends.
Chat with our AI personalities
Cheren is in the last room of Victory Road before going to Victory Road. (Meet him on Route 5 first.) Bianca is in Professor Juniper's Lab. (I think after beating Alder, I'm not sure)
When your about to get to twist mouintain on route 7(after beating skyla in milstration city), Alder will swoop down and give it to you.
you defeat team plasma and get the national dex,then battle alder
Go to the Nacrene Gym. Alder, the two Professor Junipers, and Bianca are there. After some dialog, Lenora will step out. When Alder asks if you're prepared to be the one to fight N if Alder is defeated, say yes. Then, you will receive the Light Stone if you're playing Black, or the Dark Stone if you're playing White! Your next destination is Opelucid City, so fly back to Icirrus City and prepare to head north to Route 8.
FLY: Driftviel City- From Bianca CUT: Stration City- From Mokomo SURF: Twist Mountain- From Alder STRENGTH: Nimbasa City- Top Left Building WATERFALL: RT. 18 DIVE: Undella Town