Deku the One For All Legend (Bnha multi crossover fanfic)

Prologue (Part 2) Izuku's childhood

"Just because you have an amazing quirk doesn't mean you can go and bully others Kachan!" Izuku yelled.
"And what are you gonna do about it! You can't do anything with your lack of quirk! I'm gonna be the number one hero while you'll just be a useless Deku!" Katsuki said with venom in his voice.
Izuku was defending another quirkless kid from Katsuki and his goons. After trying to defend him Katsuki and the others brutally beat him up with their fists and their quirks. Knocking the poor kid out with bruises and burn marks.
What he doesn't know is that someone was watching the whole thing. A hero in his time but a vigilante in this time looking for a successor. A hooded man walked up to Izuku. "Excuse me. Do you know this kid?" The hooded man asked with a deep voice. "N-No sir... all I know is that h-he saved me from those guys." The kid said.
"That's all I need to know kid. I'm gonna take this kid somewhere, by the way. If you want to be a hero. Don't let anyone drag you down just because you're quirkless. There's plenty of ways to train your body to becoming the hero you want to be." The man said. "Y-yes! Thank you sir!" The kid said.

The hooded man brought Izuku to Dagobah beach. The beach was littered with trash. He bandaged Izuku up and eventually he woke up. He didn't recognize his surroundings at first, all he felt was sand and he saw he was surrounded by trash.
He saw the hooded figure standing in front of him with his back turned looking into the horizon.
"E-excuse me... who are you, and where am I?" Izuku asked kindly.
"Ah. You're finally awake. I took you here to train you, you're at Dagobah beach. And my name..." He took the robe he was wearing off to reveal an old but muscular man. "...Is Kenshiro. People in my time knew me as the Fists of the North Star. Now tell me kid. What's your name?"
"I-Izuku Midoriya sir. And... i'm sorry to disappoint you sir, but i'm just some quirkless kid." Izuku said sadly.
"Disappoint? Why would I be disappointed in someone who wants nothing more to be a hero just because he's "quirkless"? I seen how you acted when those bullies were hurting that kid. Now tell me, what made you do such a thing?" Kenshiro asked.
"I don't know... my legs just moved on their own and my mind was just making stuff up..." Izuku said shyly.
"Izuku. That right there is what makes a hero. I'll tell you something. I'm 1,500 years old and have been looking for a successor for so long. People in my day called me "a God sent avenger who electrified the earth" i've been alive before quirks, which means I myself am quirkless, and I think I have found my successor." Ken said holding his hand out to Izuku. Izuku was overwhelmed, ever since he went to the doctors, he was told by everyone he couldn't be a hero and just laughed at him, he was just being verbally and physically hurt by others with no one, not even the teachers to step in!
"Izuku Midoriya, will you be my successor?" Ken asked. Izuku didn't even hesitate to answer. He was so happy that someone actually believed in him.
"YES, YES, YEEES!!!" Izuku couldn't contain his excitement, which made Ken smirk and chuckle a bit. He saw that he had the drive to be a hero.
"Now Izuku. Let me show you the power I have in store for you." Ken said as he gets in a fighting stance and punches a bulldozer completely obliterating it with one punch.
Izuku being amazed was an understatement. He saw someone who wasn't only 1,500 years old, but was SUPER strong! People only heard of him in history books, nobody knew he even existed!
"Tomorrow, we will start training here. But we better at least go tell your parents. We don't want them to think I kidnapped you or anything." Ken said.

Days turned to weeks, weeks turned to months, months turned to years.
Ken started Izuku off with basic martial arts to start with. Later on Izuku started to get into ki control. Ken taught Izuku to see spiritual energy and became a walking x-ray as well. Izuku was taught to puncture the nerves that hold quirks, be it permanently or temporarily. He was also taught how to shoot ki blasts and can move faster than the eye can see.
Katsuki one day tried to beat him up at school but to no avail. Izuku delivered a flurry of light punches that temporarily punctured the nerves that holds his quirk.
He didn't feel anything at first but he realized that he couldn't use his quirk.
"WHAT DID YOU DO TO MY QUIRK YOU DAMN NERD!? GIVE IT BACK OR I'LL KILL YOU!!!" Katsuki tried to attack him but Izuku out of self defense poked a nerve in his neck that put him to sleep (no, not killed).
Izuku felt bad. He did do it out of self defense but Izuku was never the one to ever get violent.
In Katsuki, this only poured gasoline into the fire. He constantly tried to beat up Izuku and keep him beneath him. Katsuki always kept verbally and physically hurting Izuku. Izuku kept holding back because he knew he wouldn't be any better than him if he stooped to his level.
Of course, he would accidentally knock him out by poking him in a certain nerve and feel bad about it.
Everyday after school, he would go to the beach to train with Ken. He was definitely showing results! You couldn't see it but he was definitely muscled for an eight year old!
Ken trained Izuku by cleaning up the beach and teaching him more martial arts until mastering them.