What If Goku was in KOF/Fatal Fury?

Part 1: The Beginning (Goenitz + Pilaf Saga)

Goku's arrival on Earth goes similar to canon, up until after he kills Grandpa Gohan as an Oozaru. A few days later, a old man would go investigate what happened up south not long ago. This man would be Hanzo Shiranui, the granddaughter of Mai Shiranui, who would be told to stay home. Hanzo would then discover Goku, who would most likely be fighting an animal for a fish he just got. Hanzo then shoos the animal away, picking up Goku and the fish. He then looks at the small hut nearby, and puts two and two together. "You must be Gohan's grandkid! Strange, I can't sense his ki...", Hanzo said.

Goku then cried, describing to the best of his ability that Grandpa Gohan was killed by a monster. Hanzo was saddened and in disbelief that one of his old friends had passed. "Well, that's certainly not great news... But I'll promise you, if that monster comes around again, you'll be ready for him!", Hanzo said, having a stern look. Goku just laughed, and so did Hanzo, as he took Goku home with him to train him until that monster arises once more.

For some clarification, Mai would be around 6 during this time, three years older than Goku. In the same day he brings Goku over, a military man comes over, asking him questions about an incident he was told about here. "Well, my friend Gohan was killed the other day by a Giant Ape! Well, that's what Goku told me.", Hanzo stated, pointing to him. The military man stroked his chin. "Well, that would explain the big footmarks near the house for sure. My name is Heidern by the way, sorry for not introducing myself earlier."

"Don't worry Heidern, it's alright.", Hanzo said, following up with "Anything else you found there?" Heidern nodded. "My men founded a white pod of some sort in a crater, which we believed to be a spacecraft. Given the tail on Goku, he most likely is not of this world." Of course, Hanzo couldn't understand all of the space junk, but got the jist of what Heidern stated. He did think the tail was very off. "I'll report back to you in case if Goku is  an alien. If so, I'll tell you. See you then.", Heidern said, before waving goodbye and piloting a helicopter.

A few weeks later, Heidern sent a letter confirming his suspicions that Goku was an alien. He then explains what type of alien Goku is, which is a saiyan. The letter then mainly consists of what a saiyan is, which was a warrior race that was feared throughout the galaxy. The letter does include info about the zenkai boost and the Great Ape transformation. At the end of the letter, Heidern states that he will come to check on Goku every now and then, since he has found a wandering blue-haired girl he needs to take care of. With the letter done, he puts it away, now having a training regimen in mind for Goku.

4 years would pass until the arrival of Andy Bogard to the Shiranui Dojo. During this time, Goku would train with Hanzo Shiranui and Mai. Mai would become close friends with the young saiyan, seeing that he has a big heart, despite not being the smartest. On one of their training sessions, Mai accidentally hurts herself with one of her fans. Goku then runs out, using supplies from the environment to help treat the wound to the best of his ability. It did work, but it was painful for Mai. She was still thankful though, as Goku did managed to get the wound to stop bleeding. Hanzo then took care of the wound, ending training for that day. Leona would be younger than Mai, around 9 or so.

This causes Mai to develop feelings for Goku, and eventually fall in love with him. After each and every visit, Heidern would see just how strong Goku can get in shorts amounts of time. He then decides to train Goku himself a bit, since he sees great potential in him that feels like Leona's. Speaking of Leona, she would most often join in the training when Heidern visited, and would have catching up to do with Goku and Mai. When she turns 10, Heidern decides to have her be trained under himself and Hanzo, since her natural potential for fighting shows. This would allow for Leona to grow far stronger than in canon, since she is training under two people with two or one sparring partner, give or take.