Route 9 is a shorter road connecting the Tubeline Bridge to Opelucid City, the location of your eighth gym. More usefully, it is the location of Shopping Mall Nine, which is the Department Store of the Unova region.
Just as you enter the route, an Infielder will toss you TM56 (Fling).
Shopping Mall Nine
You can't miss this place - it's a large building in the north of the route. On the first floor, the cashier sells the usual Poke Mart items. On the second floor is a Poke Ball and Mail counter, and a TM counter, but the latter has only two TMs for sale: TM15 (Hyper Beam) and TM68 (Giga Impact). Both cost 
90,000.
On the third floor, there are vitamins and battle items for sale, as well as a vending machine.
There are also trainers which you can battle:
- Waitress Flo
- Minccino (Lv. 36)
- Lilligant (Lv. 36)
1,440
- Rich Boy Manuel
- Liepard (Lv. 36)
- 5,760
- Waiter Bert
- Minccino (Lv. 36)
- Lampent (Lv. 36)
- 1,440
- Lady Isabel
- Stoutland (Lv. 36)
- 5,760
Once you've finished shopping, continue out again.
The rest of Route 9
There is dark grass on this route, and a selection of wild Pokemon, but only one new Pokemon.
- Liepard (Lv. 33/38)
- Garbodor (Lv. 31-33/36-38)
- Minccino (Lv. 32/37)
- Gothorita (Lv. 31-34/36-39, Black only)
- Duosion (Lv. 31-34/36-39, White only)
- Pawniard (Lv. 31-34/31-39)
#624 Pawniard - This chess piece Pokemon is a Dark/Steel type. While it is quite quickly let down by its major weakness to Fighting-type attacks, it's a fairly useful Pokemon in battle. It can learn Aerial Ace to cover its Fighting weakness, and Dig for Fire-types (both by TM), and gets improved stats when it evolves into Bisharp (at level 52).
Other than that, there is little here until after you defeat the Elite Four. Continue to Opelucid City!