How to counter Nunu & Willump
Let us take a look on how to beat Nunu & Willump. We will look at champions who are strong against Nunu & Willump and who are weak against Nunu & Willump. Use win rate, gold difference and creep score difference at minute 10 to find the best 
Mid champion who counters Nunu & Willump. You can already win in champion select with the right counters for Nunu & Willump. If you want to know how to counter Nunu & Willump then you need to take into account the best picks vs Nunu & Willump and the worst picks vs Nunu & Willump. This Nunu & Willump 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 Nunu & Willump or whether they played as Nunu & Willump.
Champions used by Pros to counter pick Nunu & Willump
Looking at the matches from Pros (see table Pros counter picked Nunu & Willump) we can see that they picked 
Orianna most often to counter pick Nunu & Willump. The matchup Orianna vs Nunu & Willump occured 6 times. Nunu & Willump has 2 wins and 4 losses in this matchup. Learn how to counter pick Orianna to get another perspective on the data.
Lane outcome for Nunu & Willump
When looking at Nunu & Willump 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 Nunu & Willump. The lane outcome of Nunu & Willump consists of three outcomes: Win, Loss or Draw. Let's take a look of Nunu & Willump 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 Nunu & Willump.
Conclusion
Analyze the available data and learn how to beat Nunu & Willump. To master Nunu & Willump take also a look on Nunu & Willump builds and runes for Nunu & Willump. Good luck, Summoner!