Gyarados uses moves such as Steel Wing, Dragon Breath, Dragon Pulse and Hyper Beam. This page shows the best moveset ranking for Dragonite to help a player select an individual to power up base on the moveset. The ranking is based on total attack performance. To see what is the total attack performance, the evaluation criteria, and how to see the charts, tap the link below.
Gyarados lost Dragon Breath due to the update on 8/20!
Now Gyarados may not beat Dragonite easily since it has only Bite for fast move. The most recent update take Dragon Breath away Dragon Breath away from Gyarados. For the details of the Pokemon Go update, tap the link below.
Due to the update on August 20, some species got fast/charge move which they can acquire changed or removed. Here is the list of those Pokemon and revision.
Best moveset to beat Dragonite
Since Gyarados can use dragon-type moves, it is considered as the best one to fight against Dragonite. To beat Dragonite, Dragon Breath and Dragon Pulse are the best moves for Gyarados.
Gyarados can use dragon-type moves despite its a water- and flying-type Pokemon. Those moves are super effective against Dragonite. Therefore, Gyaraods has an advantage.