This is the first episode of DBZ-Yugioh. The DBZ timeline is after Dragon Ball Battle of Gods and the Yugioh timeline is after Yugioh GX.
It was one year after Goku lost to the God of Destruction Bills. Goku was training with Vegeta when a portal sucked them in. When they woke up, they were with all there friends but also their enemies; even the ones killed. Goku could see Freiza, Cell, Majin Buu, Babidi, and even Bills. He could also identify all his friends and family like Goten and Gohan as well as Krillin and everyone else.
"I don't understant," thought Goku.
Someone named "The Creator God of Light, Horakhty" arrived to talk to them.
"I'll explain why all of you are here," said Horakhty. "You are all in the world of Duel monsters and this world has been corrupt due to many disturbances. These disturbances have sent you people of another universe here whether living or dead. This is because even your universe is starting to become corrupt so everyone responsible for causing it otr attempting to stop it has been sent here. I still do not know the true cause of this but this is all I can tell you. The only way out is collecting enough Duel energy to save both of our worlds and restoring all of you. You are all duel monsters and I'll supply you a deck from your life experiences. I'll also use my powers to teach you all you need to know about dueling."
Horakhty used his powers to give them information about dueling and gave them a deck of their own. He then teleported them to different places. Those with bonds stayed near each other.
Goku looked at his deck.
"I guess we'll all have to duel a lot. Chi-Chi, how's your deck," Goku asked.
"It's similar to your own," Chi-Chi replied. "The only difference is thta you don't have me in your deck but I have you.
King Piccolo found the crew.
King Piccolo vs Piccolo
"Son it's time for revnge," King Piccolo said angrily.
"Father, why are you angry at me," asked Piccolo.