How to counter Poppy
Let us take a look on how to beat Poppy. We will look at champions who are strong against Poppy and who are weak against Poppy. Use win rate, gold difference and creep score difference at minute 10 to find the best 
Jungle champion who counters Poppy. You can already win in champion select with the right counters for Poppy. If you want to know how to counter Poppy then you need to take into account the best picks vs Poppy and the worst picks vs Poppy. This Poppy counter data is based on matches played by Pros on patch 13.24 and previous ones. It is important to see whether Pros counter picked Poppy or whether they played as Poppy.
Champions used by Pros to counter pick Poppy
Looking at the matches from Pros (see table Pros counter picked Poppy) we can see that they picked 
Lee Sin most often to counter pick Poppy. The matchup Lee Sin vs Poppy occured 67 times. Poppy has 30 wins and 37 losses in this matchup. Learn how to counter pick Lee Sin to get another perspective on the data.
Lane outcome for Poppy
When looking at Poppy 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 Poppy. The lane outcome of Poppy consists of three outcomes: Win, Loss or Draw. Let's take a look of Poppy 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 Poppy.
Conclusion
Analyze the available data and learn how to beat Poppy. To master Poppy take also a look on Poppy builds and runes for Poppy. Good luck, Summoner!