Expositional backstory
There is a legend in the universe. They say that there are seven large orbs, each emblazoned with stars. If one gathers all seven, they can have a wish granted. Most people knew that the peaceful Namekians had created these orbs, but not many knew that a set existed on a planet called Earth as well. Two of the people who knew about the Earth Dragon Balls were a couple of Saiyans. One known as Pinich, and the other known as Burrok. The two of them had survived the destruction of Planet Vegeta, and travelled the universe together. This was because, unlike most Saiyans, they did not crave destruction. Their only desire was to become as strong as they could, so they may finally defeat each other. They spent decades training their bodies to their limit. However, they one day learnt of a Saiyan who had defeated the tyrant Frieza by becoming a "Super Saiyan": A legendary transformation said to only happen every 1000 years. Hearing about the Super Saiyan, Burrok and Pinich decided to travel to Earth, to make a wish upon the Dragon Balls there.
Earth
"Hey, look over here!" A young man called to his friend. He had tall black hair which was made up of several spikes. He was about the size of a teenager and he was wearing a blue shirt, white cape and white pants. Wrapped around his waist was a belt with a large gold buckle. Strangely enough, the man had a tail coming out of his back, around where his anus was.
"Coming Pinich!" The young man's friend replied. Unlike his friend, he was taller, with the same black spiky hair, except much shorter, with one spike leaning over his forehead. He wore strange attire; some sort of black chest plate with blue shoulder pads, three blue pads coming from the waist and skin-tight black pants. Like Pinich, he also had a tail, but he kept it wrapped it around his waist securely. He hurriedly made his way over to where the smaller Saiyan was standing, and he saw what they had been looking for: an orange orb with a picture of four orange stars on it.
Pinich grinned broadly at Burrok "That makes seven!" He exclaimed happily, picking up the ball from the ground and examining at closely.
Burrok looked at Pinich and spoke "We should summon Shenron."
Pinich nodded, and took out six other orange balls. Each emblazoned with their own number of stars. He laid them beside the Four Star Ball and spoke "Eternal Dragon Shenron! I summon you!"
As soon as Pinich spoke, dark clouds overtook the sky. The dragon balls all glowed yellow and shot a beam into the sky. The beam moved around, before becoming a long green dragon with red eyes. Two antlers protruded from his skull and he spoke with a deep, powerful voice, that seemed to echo all around the land.
"I am the eternal dragon Shenron. I will grant you any one wish. Speak your desire."
Burrok looked at Pinich, who nodded. "Our wish is for a tournament to be held. All the strongest fighters in the universe, from all of time and space will participate in it. And unlike a normal tournament, you don't lose from a ring out or anything like that. The tournament will decide who is TRULY the strongest in all of time and space!" He declared loudly.
Shenron hesitated for a minute, its eyes closed, before opening. His red eyes glowed red, and he said to Burrok and Pinich "Your wish has been granted. Farewell."
Pinich and Burrok both looked around, and saw nothing different.
"Maybe… we have to find it?" Pinich suggested awkwardly.
Burrok was about to make his own suggestion of looking for high power levels, when behind Pinich, a large blue portal appeared. Pinich turned around and saw the portal, as it quickly pulled him, Burrok and the terrain around them into it.
