Goku wins

Goku would power up to Super Sayian God. The ground would shake as Goku powered up, "Hey Riser. Come fight me" Goku would land down on the roof.

"Ready to die?" Goku would ask in seriousness. Riser would just laugh "You hurt my friends. You want to force my friends into things they don't want to do. You deserve to die."

Riser would laugh even harder, "Kid even if you used the peak of your power. Even if you trained for a billion years you wouldn't be close to my power."

"Get ready Riser." As Goku would put his hands on his forehead he would remark "I am the strongest under the heavens. I am the strongest mortal in the universe. I am the hope of the universe."

"I am the Legendary Super Sayian God Son Goku!" Goku would teleport in front of him and he would punch him in the stomach he would cough up blood and a hole of fire would close up.

"I'm immortal, kid." Riser would remark. Goku would ask the question "Can you regenerate or can you never die?" Goku would punch his jaw as he would roundhouse kick Riser.

Goku would charge up a kamehamehameha. He would fire frying Riser to a crisp. "Riser, the king has retired, The Memory peerage wins." The phoenix family mumbled amongst themselves.

"He beat Riser." Goku would power down as he would give Rias a thumbs up. "He beat Riser Phoenix. We must thank this guy." A guy with red hair would say. Goku would laugh as Issei would ask.

"Goku are you alright?" A white ritualistic circle would appear and Grayfia would appear with a taller man with red hair and blue eyes. Goku would look at the guy.

"Son Goku I saw your performance and I would like to thank you for saving my sister." Goku would look eyed "RIAS IS YOUR SISTER?" Issei would stare at Goku "How didn't you figure that?"

"So who are you because you are stronger than everyone else here?" Goku would ask. "I am Sirzechs Lucifer. One of the four great Satans."

"I didn't expect you to look like a copy of Ria's?"