Goten sparred with Goku while limiting his power level to match Goku.
After Goten finished learning, Goku wanted to test how strong Goten is so he suggested a spar.
Goten already learned how to control and limit ki while he was training fusion with Trunks so he was able to easily accomplish the task of limiting his power to match Goku.
And it was when he noticed that Goku's movements compared to him were sharper and more precise.
Goten's martial arts that he learned for Vegeta were designed to be infused with killing intent with more focus on destruction.
The martial arts that Goku uses are more focused on getting clean hits, parrying and outperforming your opponents with better decisions.
"I can understand why that is his final form," Goten said as he looked at Goku.
He saw Goku in his ultra-instinct from one of the video clips and wondered why the ability to dodge every attack and land every attack was even made into a form.
But He now understands why Goku achieved Ultra Instinct.
And he wonders if Vegeta would have a similar type of power-up that is based on the way he fights and his mindset.
"Huh? What did you say?" Goku asked Goten.
"Nothing," Goten replied.
But Goten knew that he was not Goku or Vegeta.
Trying to achieve forms that are supposed to represent them as warriors would only make him a carbon copy of them.
And he doubts that he would be as strong as them since they don't fully represent him.
He has to find a path of his own. A path that he wanted to follow for himself.
But that does not mean he cannot learn from them.
"!" Goku was shocked to see what Goten started to do.
But he was very pleased.
Goten started to incorporate Goku's martial arts into the martial arts that he learned from Vegeta.
He baited Goku with a punch to the body only to slightly tap his shoulder with a roundhouse kick.
When Goku was distracted for a few seconds when he guarded the kick, Goten went for a punch to the body again but this time it was not a bait.
Goku tried to distance himself away from Goten for a few seconds to try to regain an advantage over him and he was again surprised by what Goten did.
"Final," Goten said as he took the charging stance of Final Flash.
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At that time Goten remembers what Vegeta said to him about the Final Flash.
"Why is Final Flash charging much faster than Kakarrot's technique?" Vegeta said as he looked at Goten.
"Well, that is very simple. Kakarrot's technique focuses on gathering all the ki that he has in his body in a single area while Final Flash spreads all the ki from the body into both of the arms." Vegeta answered.
"Most of my body is also loosened when I was trying to use Final Fash to let the ki inside my body flow much more smoothly."
"Being able to gather ki in two areas of my body while it was loosened will always be faster than having to focus all of your ki in a single area while being in a stiff body posture," Vegeta answered.
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"Kamehame...." Goku started to charge a Kamehameha to counter Goten's attack.
"Kamehame...." However, in the middle of charging his ki for the attack, Goten suddenly started to change his charging stance to a Kamehameha stance.
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Goten also recalled what Gohan said to him about Kamehameha.
"Why is Kamehameha more powerful than other techniques?" Gohan said.
"Well, that is simple. Let me show you." Gohan said as he took a Kamehameha stance.
He started to gather ki in his hands.
"Can you see it Goten?" He asked.
"I don't get it," Goten replied.
"Well, do you see that the flow of the ki in my body is kind of stiff? Right?" Gohan asked.
"You are right," Goten said as he looked surprised.
"And that is intentional. Kamehameha relies on you to build your power in a single area. And letting the ki overflow while you charge it will only make it harder to control."
"But because the build-up is slow the beam ended up being a more powerful attack than most of the other attacks like Galick Gun or Final Flash. Because it was more condensed. This stance may limit the flow of ki in your body but it allows you to focus your mind in one area."
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"Haaaaaaaaaaaa." The two attacks clashed.
I see. He used the final flash stance to start the ki charging faster and changed it into Kamehameha's stance midway for more power. Goku thought in his mind.
They didn't spend much time training together as the sparring session only lasted for about four hours.
Most of the time was used on Goten's learning Spirit Bomb and Goku's other techniques.
But Goten learned a lot in such as short time as he observed all the movements that Goku made and learned all the necessary techniques that he thought he might need to defeat 21.
It would have been impossible for him to learn all of them if he was not a Half-Saiyan who was very gifted.
Goten's attack overwhelmed Goku as Goku was hit by the Final Kamehameha.
"Dad." Gohan who was watching the fight called out Goku in a voice full of worries.
When the smoke cleared Goten was standing Victorious while Goku lay on the ground.
Goku didn't look disappointed but he looked kind of happy.
"First, Gohan. And then my second son from the future has also surpassed me. It seems like I am leaving the earth in a much safer place." Goku said as he looked at the sky.
"What did you say, Dad? Why are you talking like you are going to die?" Gohan asked Goku.
Then Goten remembered that this variant of Goku was the one who sacrificed himself to defeat Cell.
Goten smiled before his mind was returned to the present.
The events that he experienced in this room didn't happen but he still keeps memories of it as Goten opened his eyes to find himself in the pendulum room.
But now as a better martial artist.