Ah, good old Tubeline Bridge. You can finally access it now and head westbound (although it will look like you're traveling south due to the camera angle).
The Battle Girl walking in circles a little south from the entrance will give you TM43 (Flame Charge) after talking to her. Flame Charge is a weaker Physical-based Fire-type attack that raises the user's Speed by one stage afterwards. It only has 50 power, though, so it won't do a lot of damage, but it can be helpful for some Pokemon.
In the gate on the other side of the bridge, talk to the Scientist and he'll give you an EnergyPowder. Uh, ok. That's not going to do you all that much good, though, but whatever.
Now just head further west onto Route 8!