Those teemo stats
I think it's safe to say leblanc's winrate decreases vs teemo because shrooms are very unkind to her. Also, at least in the early game that blind can help prevent damage from hextech revolver and late game it can hurt her even more if she decides to build lich bane (personally that's not my favorite leblanc build, especially with the new items, but it was still a popular one for a while)
Never play singed and teemo on the same team, even if you have a Casseiopeia just don't. That invites the enemy to just go all the magic resist they want and run you down. Maybe that explains why Zed works so well while playing on a team with Teemo, along with Master Yi, Yasuo, Talon, and Kayne, and why XIn's relative playrate increases so much while playing with him? It doesn't explain why Zoe takes second place as his most successful ally though, anyone have any thoughts on that?
Lee sin... In addition to being an AD champion who will be doing more damage to opponents who build magic resist, he can jump to Teemo's shrooms, so maybe that explains why people like to pick Lee when Teemo is on their side...
I love talking about stats and thinking about the reasons why they are what they are.