Help with oasis 2nd battle

Hi, I've been stuck on that 2nd boss for i dont even know how long. I come back to the game, can't win and leave (im personally overdramatic, I am aware lol)

This is my first time playing a pokemon- like game. With different ways to fight and different "elements" that effect how a fight goes. I am so stuck.

Is there anyway anyone could teach me how this works? And some pointers of how to get past Mr sewer lab guy with bird who one-shot my whole team?