In Fairy Tail 2014, there is a common battle song that plays. An example is when Juvia fights Aries in the desert in episode 37, when Aries makes fun of Juvia while she is on the ground.
What is the song?
It depends on which part of the battle scene you are talking about.
Towards the beginning (When Aries first arrives) is unknown to me. It is possibly one of the 2016 versions of the song that I still haven't listened to.
At the end (when Juvia smashes the coolant on the magic mobile) that song is "Titania Mau". It is also played when the returning of the dragons in the Tartaros chapters (Grandeeney (could also be spelled Grandeena), Igneel, Metalicanna, Weisslogia and Skiadram)