What's lacking in the answers IMO is HOW to play against a Leblanc not as a specific champion, but in general.
Leblanc has a very high damage output, but is probably one of the squishiest champ in the game. After the removal of the silence on her Q-proc laning against Leblanc has become much easier - You can now efficiently trade back once she has used her combo. But not only that, after her Q+W (in lane) you typically have a 15 second window to exploit the hell out of her cooldown (W CD: 18/16/14/12/10).
The important thing to do against a Leblanc is to push when she has CDs! Even if she just took you down to 50% with one Q+W, don't be scared - Retaliate! The one thing you have to be obs for is a Q+E as her Q has a low cd. She also has terrible waveclear unless she is going to be using W on minions (which doesn't even clear the wave early and would put her at great disadvantage when it comes to trading). Therefore when you have the upper hand you can and should push her to the turret and make her focus on lasthitting as you poke her.
If you can easily communicate with the jungler, be it that you're a fast typer or using voice-chat, you should inform him/her whether or not the Leblanc is being aggressive with her W. The jungler should stand in a bush and wait for her to use Distortion (W) and then go in towards the pop-back for the gank. If you are duoQing with a jungler, you might consider choosing a champion with hard cc mid as to organize your ganks.
I've seen a lot of players going Galio recently as you can negate her combo pretty well with your shield (W) and stacking MR is a natural thing on him.
Syndra counters Leblanc for various reasons, most mentioned above. But IMO the most important being that she can actually stop her midair with her E (when she W), like Galio, completey negating and often with a follow up stun to burst her down.
Zed and Yasuo can both dodge Q+W by using their own dashes if you're good at predicting them. Zed can also negate a lot of damage with his ulti.
Zed (Faker) vs. Leblanc:
Could be an idea to have your own runepage where you replace yellows with hp instead of armor and flat mr blues instead of scaling.