Only Gohan & Piccolo remained after the battle with Raditz. Gohan seemed reluctant to train
with Piccolo 'cuz 1. He's Gokou's worst enemy and 2. Gohan doesn't know about his powers.
Piccolo then threw Gohan into a nearby
mountain an Gohan blew up the mountain just
before he hit it. Gohan then believed him.
Piccolo then told him of the oncoming threat and
began the training. Except Piccolo's training
wasn't the type of training Gohan [or anyone
else] expected.
Piccolo's training was to leave Gohan out in the wilderness for a few months so Gohan wouldn't be as much as a pansy and would know how to fend for himself. Gohan of course cried and cried but Piccolo flew off out of Gohan's sight.
That night Gohan woke up when the moon was full and went Oohazru. Piccolo tried to stop him, but ended up getting slapped around like a... well I think the older reader's might know what. Piccolo then realized the moon had caused the transformation, so he Makankousappu'ed it, the moon blew up and Gohan return to normal. Piccolo realized the tail was the main cause of it, so he popped it right off.
Meanwhile Killyn and Bulma were busy getting the world's champions together and tell them about the Saiyajins. Later on at Kame-sama's palace Killyn, Yamcha (the so-called Gokou look alike), and Yajorobe (the fat ass). They trained at Kame-sama's for the remainder of the year.
Tienshihan and Choazu trained together for the rest of the year as well.
While in the afterlife Kame-sama persuaded Demon Lord Dalo (King Yamma, the HUGE guy at the HUGE desk) to let Gokou train with Kaio-sama at the other end of snake way (snake way is a path that looks like a snake, with clouds below it leading to Hell (or for you US DBZ fans HFIL (Home For Infinite Losers (Mad gay!!))). He agreed and Gokou began the 10,000 mile trek across snake way.
(I'll finish up with Gokou then, with Gohan & Piccolo, ok? :) Skip ahead to Gohan & Piccolo)
Gokou was running and running and running, and guess what? He ran some more!! While on the path, Gokou met some guy who's job was to clean snake way on one of those street cleaners. Gokou caught a ride on the back of the machine and got some long needed sleep. While asleep, the street cleaner hit a bump and Gokou fell off the behemoth machine, off of snake way, below the clouds, and into the depths of Hell.
While in Hell, some ogres said if Gokou could beat them both in a competition, then they would show him away back onto snake way. The first guy wanted Gokou to wrestle with him sumo-style. Gokou made some wind by palm striking nothing VERY fast and knocked the guy out of the ring. The second guy wanted Gokou to race him and after a while of different types of races, Gokou tricked him into winning (it's stupid so I won't go into details).
The ogres showed Gokou the way back to snake way, Gokou followed the dark tunnel and at the end Gokou appeared at of Demon Lord Dalo's desk. Gokou then ran back to snake way and began again. Gokou got farther than he did last time and in the distance, he saw a house. Gokou proceeded to Saiyajin book over to it. He assumed that it was Kaio-sama's place.
Inside he met Princess Snake who greeted him warmly, however, she slipped some sleepy stuff into Gokou's food and she was about to eat Gokou, when he suddenly woke up. He was somehow inside a giant snake. He mega-flew out as fast as possible and escaped.
Gokou then made it to the end, and he saw a small planet in the sky, so he jumped to it. On the planet, the gravity was 10x Earth's gravity so he had some trouble. He met up with Kaio-sama and began the training. The first test was for Gokou to catch Kaio-sama's pet, who just happens to be the fastest monkey in the universe, named Bubbles, AND he was used to the heavy gravity. Gokou blew giant moose cock and didn't even come close to catching Bubbles. Kaio-sama then said it was time for food.
After eating Gokou easily caught Bubbles. Next was the second test. Gokou had to hit Gregory, the fastest flying cricket in the universe, with the heaviest mallet in the universe. Eventually he did. Now the real training began.
Kaio-sama taught Gokou the Kaio-Ken technique, which multiplies everything by a certain amount (speed, strength, power...), but uses stamina quickly. He also taught him the Genki Dama (Translation: Spirit Bomb). The Genki Dama uses energy from the planet (mountains, rivers, oceans, animals,...) and transforms it into a [usually] large (depends how much power (Its power is determined by its size and natural resources.) the planet has.) energy ball with extreme power. And he taught these to Gokou over the remaining months.
Now back to Gohan and Piccolo.
Gohan spent about half the year in the wild, getting his own food, saving his own hide from deadly animals, and staying alive. Gohan got significantly stronger (around the 800's I think), and a lot braver. Gohan later used his book smarts to make a boat/raft to get back home. He makes it. He tests it several times, fixes it up, and tests it again. Until he's ready to set sail.
A large storm came and destroyed Gohan's raft and he awakened at a town populated with orphaned children. These kids are constantly trying not to get caught by the welfare people and Gohan (being very strong compared to 99.9% of the humans) helps them out a lot. However, one by one the kids are caught until the kid's leader (about age 10) gives up, realizes the kids would be better off at a foster home, and steals a hover car and drives away with Gohan.
Gohan yells at him, but the kid doesn't care. He kicks out Gohan, they say their good-byes and Gohan runs home (somehow, he was very close to his house.). Gohan finds his house and sees Chi-Chi (yes, she knows all about Gokou and Gohan) looking at a photo of the family. Gohan reconsiders and decides to save the planet for not only man/Saiyajin kind, but also his family. He thinks, "Don't worry Mom, I'll be home soon," and takes off. Chi-Chi senses (No, not power level sensing) Gohan's thought and looks outside, but finding no one. Gohan's rushing back to the wilderness and meets Piccolo, who knew he'd be there, and he asks Gohan, "What is your mission?!" and Gohan replies, "To save the Earth." They leave and go off to start the real training. And they train hard for the rest of the time.
Soon after Raditz died, the two remaining Saiyajins, Prince (or actually King) Vejita and Nappa. They set a course for Earth, but decide to take a rest stop on the way. They arrive at the planet Arlia. They kill the evil dictator of the planet. The people think of Vejita and Nappa as their savior, but Vejita blows up the planet (he's a bad guy, he's allowed to blow up a few planets). And then they head straight for Earth.
The year has passed, everyone is much stronger than ever. Everybody rests up for the big battle. Bulma, Oolong, Master Roshi, and Puar wish Gokou back to life with the dragon balls. Gokou's halo is now gone, but he has to run back to the gates of the afterlife by Demon Lord Dalo. Kaio-sama gives him new clothes, which repel small attacks, and has his symbol on the back. The rest of the Z team gathers up and gets ready. Vejita and Nappa arrived.
Vejita and Nappa blow up a city, then head for the strongest power readings, Piccolo and the rest. They talk, Vejita wonders why a Namek is defending Earth and Piccolo finally finds out why he was not like the humans. They do some more talking, and yada-yada-yada, the fight begins. Nappa uses little plant men called Sybamen (I dunno how it's spelled.), 6 of them to warm up and test Earth's warriors. But, Gokou still hasn't arrived.
The Z team takes a beating, but kill 'em all anyway. Now, it's Nappa's turn. The almost real battle begins. They all team up against Nappa and get the snot rocked out of them. Choazu sacrifices himself to stop Nappa, but Nappa survives easily. Tienshihan's pissed. He pretty much goes Super whatever the hell race he is. Nappa beats him down and chops off Tienshihan's left hand (Ow!! What's with the chopping off hands?). Nappa kills Yamcha, Tienshihan, and... charges up a big blast. He shoots it at Gohan but Piccolo gets in front of the blast just in time and dies. Gohan's pissed now. Gohan and Killyn team up against Nappa and get the shit kicked out of them. But, someone arrives when he's needed most... Son Gokou had come at last, with some senzu beans from Karin (The cat guy). Gives some senzu to Gohan and Killyn and he's pissed, of course. Now Gokou and Nappa go at it.
Gokou beats the hell out of Nappa, without breaking two sweats. Vejita's pissed at Nappa for losing so bad and tells him to calm down (NEVER tell a Saiyajin to calm down, anger is what makes them stronger!!) and that he's becoming too careless in a blind rage. Gokou still kicks his ass. Vejita tells Nappa to stop 'cuz he's too weak and Nappa pleads with Vejita that he's able to kill Gokou. Well, Vejita doesn't like being a nice guy and blows up Nappa on the spot. Gokou's surprised, but also glad (Although he'd never admit it.) 'cuz there's one less enemy. Now the REAL fight begins.
Gokou's still angry, Gohan and Killyn have enough strength to get the hell outta the way. Gokou begins to charge up and test Vejita's abilities. Well, it turns out, Vejita's not much more powerful than Nappa and Gokou's slaps him around. Vejita tries harder and lands a few good hits, but Gokou decides to use his Kaio-Ken attack by 3 times.
Gokou basically opens up a 24-pack of Whup-Ass on Vejita. Vejita's still kicking and Gokou begins to do a Genki Dama. Vejita is pissed and gets an idea. He creates a ball of light and sends it to the sky. Then, Vejita begins to transform to Ooharuzu.
Gokou is pretty much shitting in his pants right now, but still forming the Genki Dama. Vejita hits Gokou and Gokou loses his concentration and is now extra screwed. Vejita explains to Gokou that while in that state his strength, speed, hearing, sight... are all multiplied by 10. And Vejita (unlike Gohan) has control of himself while in that form.
Vejita beats the hell out of Gokou. Killyn and Gohan want to help but know they can't. Killyn thinks he can make a Kienza, while Gohan distracts Vejita, to cut off Vejita's tail. Gohan sets off to lure Vejita away form Killyn, Killyn makes a Kienza, but right before it hits, Vejita jumps and dodges it with ease. Vejita explains that his giant ape ears aren't just for show, for they can hear a pin drop about a mile away.
Yajorobe joins the fray, but is too chicken to fight. Vejita grabs Gokou and begins to squeeze. Yajorobe has a sudden burst of courage and cuts off Vejita's tail with his Kitana (this is the real way you spell kitana, not katana). Vejita's pissed and slowly shrinks to his normal small size and releases Gokou. Gokou tells Killyn that Gokou still has a small portion of the Genki Dama and it should be enough to kill Vejita. Killyn is reluctant but Gokou says that if he has a pure heart of good it'll work. Killyn blasts at Vejita with it, but Vejita jumps into the air and avoids it. However, the Genki Dama is headed towards Gohan. Gokou tells Gohan that if he puts his hands out, it'll bounce off of him so he should aim it at Vejita. Gohan does it, it bounces off and catches Vejita dead on. Vejita gets the hell blown outta him. Gokou, Killyn, Gohan, and Yajorobe believe that Vejita's dead, but Vejita's body hits the ground hard (see the pic). And with his last ounce of strength he gets his space craft to go to him using a remote, climbs aboard, and flies away.
Bulma, Mater Roshi, Oolong, Puar, and Chi-Chi arrive and fly Gokou, Gohan, and Killyn to the hospital. And Vejita flies to his so-called headquarters and is put into a regeneration tank.