This Seeking Tech guide will explain how you can beat Nebulax without taking any damage. Use the following video as a reference:
The difficulty of this fight depends on the roulette wheel.
If you landed on the monkey space, then you will need to dodge the yellow circles. Afterwards, pick up any pellets with your power-up and then throw them right back at the boss. Keep doing the same thing to end this segment.
If you land on the octopus space, then you will need to use the power-up to avoid some barriers. You have to inflate to avoid the low barriers and deflate to dodge the high barriers. Try to deflate immediately once you clear all the low barriers so that you can easily avoid the high ones. Once you manage to successfully dodge everything, inflate the squid to end this section.
If you land on the frog space, you need to jump over the shockwaves created from the hammer. Afterwards, attack the bottom of the hammer. Once you manage to break both sides, grab the head and swing it at Nebulax to end this part of the fight.
If you land on the magnet space, you need to avoid the shadows while picking up the broken metal parts. Once you gather enough metal, throw it back at Nebulax to end this segment.
If you land on the dog space, you need to get away from the shadows to avoid getting stabbed. Try to use your power-up to quickly get out of the way when the shadows darken. You should also try to avoid getting close to the edge since you may end up being trapped. When the sword gets stuck, break the sword with your power-up. Once the sword breaks, Nebulax will throw the handle at you. Use your power-up to send it right back to him to end this portion.
If you land on the skull space, then you will need to defeat a bunch of enemies. Afterwards, you have to repeat the same roulette spin over again until you land in a different space.
It is also important to note that Nebulax will cheat on the third roulette spin by moving the landing spot to the next one on the left. So, you should make sure that the next space isn’t a skull.
Once you clear a section with a power-up, you should avoid the enemies and instead run directly towards the UFO. Attack the hands of the alien and then break the lock to end the phase.
After defeating Nebulax initially by breaking all the locks, he will show up again shortly afterwards. When you get on the controller, hold down R2 to see where you are shooting. You can then shoot down any objects that are thrown at you. Once you destroy the ship, attack the core of the UFO to end this fight.