Disclaimer I don't own Dragon ball Z or the justice league they are owned bye dc comics and some dude named Akira toriyama.
This is slightly AU flash wont be able to use the speed force.
Prolog.
"What? What do you mean he's coming here?" a voice shouted a mix of fear and raw terror "contact krypton we must let the council know klor rel" a elderly gentlemen in a military uniform declared he was general Mar Rel a general from krypton and commander of the last colony the only one out of the system they had no contact with their home world in many days mostly because of radio silence order.
They where at war, war with a despot well it was not really a war it was more like a stand off Krypton had been keeping an eye on the changeling Frieza for some time his empire was vast and even the new gods stood out of his way. When his minions came a calling most of the galaxy tended to shut up and do as they commanded for fear of their master more then anything. Now lord Zarbon was coming here and he heard it was with a group of saiyans elite. A cold shiver ran down his spine as he heard his son's next words "sir, our world she's g-gone!" he yelled, "Our son went nova!"
"What! Dammed Frieza" he yelled believing Frieza was at fault he had heard rumors about the beast being able to level worlds but he never thought it would happened now.
Grief seized him and he fell to the floor in tears "get out a distress signal some one must hear our voices some one will help" as he said that a sound of space pods could be heard.
It seemed a legion of saiyans had landed on their territory Zarbon was here he brought company. The men quickly mounted their defense and a bloody assault waged. As tears rolled from his face he stood and made his way outside to watch the battle. They were not out numbered and their technology was great they where gaining the upper hand and taking insane casualties doing so.
From Space Zarbon and another green alien watched the battle their scanners picking up the dead. With an arrogant sigh Zarbon looked to the green alien "do you suppose Frieza would kill me if I burned this planet to rock saiyans monkey's and all?" he asked mused bye the last sons of krypton will to survive. It was rather ironic, they were headed to Krypton to blast it out of the heavens and yet it's weak sun blew it away for them. The idea of Returning home early was neat there was a little slave girl waiting for him.
"I don't think so my lord he seems to be, shall I say more and more disgruntled with them then I have seen him feel to most" he commented. Zarbon nodded "indeed well very well then"
He stretched his hand outward and a ball of glowing energy spiraled to the planet-fallowed bye another and another and another. Bright orange and red flashes echoed about the world rainbow colored clouds decorated the world witch had been burned now into the very core nothing was left it was shattered broken twisted, lord Zarbon as one of Frieza most ruthless nobles and he was said to be second to none save only his master. The two green aliens watched as the world slowly died filthy saiyans trash had melted away in the lava the krypton race was now gone Though Frieza never specified why he wanted them gone he heard the technicians bring up how in prolonged exposure to the yellow sun they become very powerful. He wondered if Frieza feared them or just considered them an annoyance not worth the time addressing. Then again why would he question his orders, for now it was back to the empire back to his bedchambers and his slave girls?
Little did he know he would face a man of krypton again in thirty years.