At slug's spaceship, there was frieza's spy watching everything. He was happy learning about the Dragonball and that it grants wishes from slug. Then he also heard slug say the one thing his lord Frieza was afraid of and that was a super saiyan. And that said super saiyan was fighting right in front of him. He wanted to complete his mission for his lord frieza at any cost. He then stopped worrying for his safety and sneaked out. Then he boarded a stray space pod and blasted off of Namek. Nail saw someone leaving and fired at the space pod. The space pod got damaged and the coordinates changed and the communication system got damaged. But the alien survived and flew in an unknown direction.
Back at Namek, the intense fight was going on. Goku was now fully adapted to slug's style of fighting. He started pushing him back. Slug had enough of this and he finally smirked. He then pushed Goku away and transformed into a Giant. The scouter in mint's hands started beeping once again.
39 million
50 million
75 million
90 million
99 million and then beep beep overload. Cannot compute. Shutting down. Mint and Nail both got scared at this new development. They thought that Goku was going to win seeing that he started to have an upper hand, but slug increased his power so much higher. Mint started tearing up. But Goku smiled and shouted "Kaioken times 10!!Ahhhh!!". Mint tearing up was pressing the scouter button to know Slug's power, and it started beeping again reading Goku's raising power. Beep....beep....
35 million
50 million
85 million
90 million
97 million. It stopped at 97 million. Goku's red aura increased significantly and slug's minion was scared seeing the reading. His lord slug's total power level reading was 105 million and this Saiyan boy reached 97million. He ran over and reported "Lord slug, the saiyan's power level increased once again. It's showing 97 million." The giant slug's laugh abruptly stopped and his face had a distorted expression. 97 million power level in the kids body is nothing to scoff at. Slug has sacrificed his speed for power by becoming huge. But if the power gap is not much different, then he will only be a bigger target.
Goku was smiling ear to ear and then he moved towards slug and started his attack. Slug waves his hands everywhere trying to catch Goku, but Goku was too fast and small for him to catch. Goku attacked slug at every opportunity and he had an upper hand. Nail on the other hand didn't know what to say. "How much power are you still hiding Goku?" He murmured and thought 'Now I see why Goku wasn't scared of slug'. The battle continued and slug was irritated and angry beyond measure. He then thought of destroying the planet and everything within. He no longer cared about the Dragonball, or he totally forgot about it in rage.
Slug then started charging a Giant energy blast pointed at the planet and everything around him. Goku seeing this, his smile vanished and he too started to charge a Kamehameha wave. Both their power skyrocketed. Slug's minions were scared. The spaceship power meter started beeping and reading their powers. Slug's blast stopped reading at 160 million. Goku was around 110 million. Then both of them fired at each other. Slug's beam overpowered Goku's Kamehameha. Seeing this, Goku gritted his teeth and shouted "Kaioken times 15" and his Kamehameha became bigger and matched that of slug equally. Slug seeing his beam stop, shouted in shock "What? How is this possible? His beam is as strong as mine".
The whole planet Namek could feel the tremendous power of the energy beams. Guru sighed and prayed for Goku's win as he was the last hope for Namek a he knew that this showdown will decide the future of Namek. King Kai also crossed his fingers as it looked like the final showdown between the two. Nail gritted his teeth seeing the powers of the two thinking he has a very long way to go before he can fully protect his people. Mint was scared shit and couldn't make out anything else. She was on her knees hiding behind Nail as she couldn't take on the shock waves. She couldn't make sense of anything as the scouter said "Unable to compute". And she already lost her rational thinking. Today was a huge blow to her.
At the blasts were stagnant in the middle without moving in any direction, Goku in a final attempt shouted "20 times Kaioken" his power suddenly skyrocketed and the Kamehameha blast overpowered slug's blast by a long shot and hit slug creating a hole through his stomach and vaporising left side of his body. And the blast travelled into space. Giant Slug slumped down to the ground and fell face first. Goku was exhausted and panting heavily. His body hurt like hell. He chewed the senzu bean in his left cheek and his body got rejuvenated, but his mind was still tired. The mental toll it took to fight slug was far higher than he expected. It was his first real battle against a stronger opponent.
Seeing Goku win, everyone was happy. Nail flew towards Goku to check on him. King Kai was also relieved seeing this. Slug's minions were scared shitless. The last reading in the scouter was 210 million. Goku's power was 9.7 million and with 20x Kaioken, it raised up to 194 million. Then with the Kamehameha, it reached 210 million. Slug didn't stand a chance at all. The minions didn't know what to do. Goku after seeing Nail arrive, smiled at him. After eating the senzu bean as he was exhausted, he received a small zenkai and his power level reached 10 million. While Goku was distracted smiling at Nail, he shouted "Goku watch out"