So apparently people are complaining that they can't get past the first boss? LOL Not gonna lie, it was really tough but the trick is to stay in the air as much as you can and take him down with your sword. Took me 7 attempts to beat it and I'm an "average" gamer. Someone said they took over 100?!?
You gotta be quick with your decisions and even quicker with your mech. If you time things right, you can move around fairly quickly between the ground and air fights. Each boss fight is different so being adaptable is the #1 thing to help you be successful.