How to counter Zyra
Let us take a look on how to beat Zyra. We will look at champions who are strong against Zyra and who are weak against Zyra. Use win rate, gold difference and creep score difference at minute 10 to find the best 
Support champion who counters Zyra. You can already win in champion select with the right counters for Zyra. If you want to know how to counter Zyra then you need to take into account the best picks vs Zyra and the worst picks vs Zyra. This Zyra 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 Zyra or whether they played as Zyra.
Champions used by Pros to counter pick Zyra
Looking at the matches from Pros (see table Pros counter picked Zyra) we can see that they picked 
Senna most often to counter pick Zyra. The matchup Senna vs Zyra occured 7 times. Zyra has 5 wins and 2 losses in this matchup. Learn how to counter pick Senna to get another perspective on the data.
Lane outcome for Zyra
When looking at Zyra 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 Zyra. The lane outcome of Zyra consists of three outcomes: Win, Loss or Draw. Let's take a look of Zyra 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 Zyra.
Conclusion
Analyze the available data and learn how to beat Zyra. To master Zyra take also a look on Zyra builds and runes for Zyra. Good luck, Summoner!