She could have spent a bit of time grinding up to level 8 which would increase charged attacks' power by 33% and make the battle one fourth shorter (that would definitely help in this fight).
First boss (Mortarmech) is a test of endurance, second boss (Nosferatu) is a test of speed and this one's a test of the player's timing and overall skill.
The upcoming fourth boss battle will rely on strategy. :)