Our second major boss battle.
The first thing you should know about the robot is that it is FAST. In fact, it will often shoot in and out much like Knack, but it is faster and glows yellow when it does this. It will do this all throughout the fight. Also note that the majority of the time he walks around with his fists up in a guarding stance (meaning you can't hurt him when you punch him).
During the first part of the fight, the robot will often dash in at you and do a three-hit combo. You want to dash away when he does this, then come in from the side and smack him.
Pretty soon he'll realize that he's going to have to amp it up to hurt you. When Gundahar says "retreat" (or something like it), the robot will pull back to the side of the arena and charge up some shots. He will then shoot three fireballs at you. Stay on the move and dodge the third one with a dash. These fireballs *hurt* a ton and will stay on the ground for a short while.
After that its back to your sparring match. He adds in one new very deadly attack this time: he will charge his fists and walk towards you while not guarding. If you get close, he will spring into action and start a series of fast (and deadly) punches, finishing with a haymaker. It's best to get close to him and dash away at the last second in order to trigger his attack. You can then dash up to him when he does his final haymaker attack and get in a hit.
After sustaining more damage from you he will throw in one final move: he will retreat to the side of the area and launch a spinning disk at you. You need to do your best to avoid this at all costs: if it hits you (and it likely will at least once: it is fast - although you are reading this guide and do have some warning) it will trap you in a circular cage. This allows the robot to walk up and hit you (you will usually only take one hit if you dash away as soon as you can).
And that's it! Keep punishing him after his attacks and keep up your dodging and you should emerge the victor.
Watch the many scenes between this chapter and the next. They are pretty good.