How to counter Teemo
Let us take a look on how to beat Teemo. We will look at champions who are strong against Teemo and who are weak against Teemo. Use win rate, gold difference and creep score difference at minute 10 to find the best 
Top champion who counters Teemo. You can already win in champion select with the right counters for Teemo. If you want to know how to counter Teemo then you need to take into account the best picks vs Teemo and the worst picks vs Teemo. This Teemo counter data is based on matches played by Pros on patch 15.14 and previous ones. It is important to see whether Pros counter picked Teemo or whether they played as Teemo.
Champions used by Pros to counter pick Teemo
Looking at the matches from Pros (see table Pros counter picked Teemo) we can see that they picked 
Sion most often to counter pick Teemo. The matchup Sion vs Teemo occured 8 times. Teemo has 5 wins and 3 losses in this matchup. Learn how to counter pick Sion to get another perspective on the data.
Lane outcome for Teemo
When looking at Teemo counters you will notice that win rates alone are not conclusional. Therefore we provide an overview (see table Lane Outcome) where you can see the lane outcome of Pros who played Teemo. The lane outcome of Teemo consists of three outcomes: Win, Loss or Draw. Let's take a look of Teemo lane and match outcome for specific matchups. Considering the lane outcome and the match outcome of a specific matchup, might enable you to find the right counter for Teemo.
Conclusion
Analyze the available data and learn how to beat Teemo. To master Teemo take also a look on Teemo builds and runes for Teemo. Good luck, Summoner!