In this story goku is the only remaining Saiyan not even paragus or broly are alive before king vegeta banish broly paragus killed vegeta and made him self as king and then immediately freeza ordered all saiyans to return bardock knowing what freeza plan sent goku to earth it is too late to inform raditz about freeza plan freeza destroyed planet vegeta and all saiyans later he killed vegeta, nappa and raditz as he was more feared and vegeta was becoming stronger due to his missions so he eliminated him.
Goku was on earth he was found by Gohan an old martial artist who took him as his grandson he trained him he helped him to control his oozaru to a extent kami helped him to master it so he kept his tail, so Gohan is not dead and the events of dragon ball went same except he didn't married chi-chi.
5 years has passed since 23rd martial arts tournament during these years piccolo tried to kill goku but goku defeated him easily as years went piccolo mellowed down and goku continued on his weighted training his weighs are upto 1 ton and piccolo and goku had a sort of rivalry and became friends they both trained together and grew stronger and 9 years had passed since 23rd tournament.
One day south city was destroyed when goku and his friends arrived they saw two teenage twins destroying every thing they revealed themselves as android 17 and 18 how they were made by gero to take revenge on goku for destroying red ribbion army and how they killed gero.
Goku and his friends were no match for them as they are 100 times stronger than goku, here goku and piccolo power levels are 10,000 and androids 17 had 1.5 million and 18 had 1 million power level goku couldn't scratch 17 as 17 got bored punctured goku in his chest killing him instantly all were shocked then they understood they are just toying with them not knowing what to do krillin said if they can seal them as they saw it in 23rd tournament by piccolo so they formed a plan and separated them chaitozu using his psychic powers paralysed 18 then piccolo used mafuba on her and sealed her instantly and took a senzu bean immediately as it almost killed him so for 17 tien and piccolo together sealed him after sealing them both they went to check on goku but his body was not there they were afraid if his body was destroyed but kami assured them he took gokus body to allow him to train in other world as it might be helpful for future threats.
But its difficult for them to convey gokus death to his grandpa which made him devastated but they assured him he went to train and will revived in a year.
In other world it took him 10 days to reach immediately the 10 times gravity along with ton weight took toll on him after introductions goku told why he is there so king kai agreed to train it took him 2 weeks to get adjusted he trained a lot in six months he learned kaioken and spirit bomb during this six months king kai noticed gokus tail taking out from his pants then king told about his origins which surprised him and leanred that he is the only remaining Saiyan but when he learned how saiyans destroyed other world he was infuriated and disgusted and seeing goku from six months understood than goku is pure hearted so he trusted goku.
Later he asked king kai if there is any thing he can teach king kai pondered and decided goku to place where warriors in other world lived he met yadratians metomorains and namekaians he was surprised find that kami and piccolo are also aliens he learned instant transmission and fought with powerful warriors who are more stronger than androids even with increase in his power he couldn't even scratch them when he decided to learn spirit control and forced spirit fission his time was over and he went to kingkai as he is going to be revived.
"thank you king kai for training me" said goku bowing.
"no problem goku its quiet interesting to train you and moreover to find a Saiyan with pure heart" said king kai.
Then the halo on his head disappeared he then instant transmissioned to lookout where all his friends including bulma and grandpa Gohan, master roshi are present he was glad to meet them he told about his training and he told them that he is an alien belonging to extinct race and he is the last of them and more surprise was when he told that kami and piccolo were aliens and belong to race namekains and he told his training and techniques they noticed his power was astronomically high.
While goku was dead they found geros lab and found android 16 and about cell which they destroyed immediately and found blueprints for androids so bulma reprogrammed 16 and waited for goku to return.
So they explained to goku what happened that how gero kidnaped 17 and 18 turned them to androids so bulma said she can reprogram them so they can live their lives to which they all agreed.
So they released them but before they could attack bulma used the remote and shutdown them then reprogrammed them which took more time than she expected and removed the bomd, while bulma was doing here work goku and his friends having a chitchat.
"hey goku how powerfull you have got" asked krillin.
"I don't know but a lot probably stronger than androids" said goku.
Then goku raised his power which shook the earth they were surprised.
"your power is nearly 100 times stronger" said piccolo.
"really I didn't think I will increase that much" said goku.
"there is a lot of power to catch" said krillin.
"but you all can reach if I didn't go to king kai I wouldn't get this stronger hey piccolo can you increase the weight of my clothes" asked goku.
"why?" asked piccolo.
"with the training I got ton is light as feather with increase in weight I can get more stronger" said piccolo.
Bulma completed her reprogramming when they were awake they told them what happened they both were were thankfull they decided to wait for some time before leaving as bulma insisted.
Its been six months goku came back to life he is continuing his training but he realised that increasing weight is not as effective as gravity he tought to go to king kai again but kami refused and there is no option for hyperbolic time chamber so he asked bulma if she can build a gravity chamber it took her a month to complete which can go upto 100 times goku invited his friends to train under gravity it took them some time by the end of six months they are 50 times gravity as humans took more time to adapt to higher gravity goku is doing gravity training along with weighted cloths as well as piccolo.
Its been a year goku was revived they all got stronger goku being in top piccolo being second tien third and krillin they all learned kaioken and instant transmission fourth as yamcha decided to pursue his baseball career and goku and bulma were married as they realised their feeling for each other and krillin and 18 started to have a relation ship.
Goku using dragon balls asked shenron all knowledge of saiyans he got information on how they get stronger from each fight and supersaiyan and legendary super Saiyan and super Saiyan god which required six saiyans he tried to reach super Saiyan but for the time he didn't had push to achieve or emotion for it.
A year later twins were born for goku he named one Gohan and other trunks Gohan has back hair bule eyes and trunks his usual hair and eyes his facial feature resemble goku more they were also born with tails.
Its been two years Gohan and trunks were born one day they all noticed some powerlevels hovering above earth they saw a ship came from it group of soidiers came began to destroy but goku and his friends stopped them all, some time later a team named giny force arrived goku decided not to step in as they are not worth his time his friends took care of them.
"whats happening here why suddenly random aliens attacking earth" asked krillin.
"I think they are sent by freeza" said goku.
"Who is freeza?" asked piccolo.
"freeza is a evil tyrant who rules over the universe and destroyes every one who opposes him and he is the one who destroyed saiyans" said goku.
"do you think he might come?" asked tien.
"I don't know from what king kai told me he doest care about his men but there is a chance he may come to find who destroyed his force so easily" said goku.
"so we need to be prepared" said piccolo.
"Yes" said goku.
"hey king kai are you there" asked goku.
"Yes" they all heard a voice in their head.
"I think you know what happened?" asked goku.
"yes I am observing all whata happening recently freeza went to namek for dragon balls to get immortality" said king kai.
"what!" exclaimed goku.
"why didn't you told he probably destroy them" yelled goku.
"don't worry they out smarted him it seems namekian dragon balls needed namekian tongue to use they used that and teleported freeza from namek and teleported the planet to new location so he cant find them" said king kai.
"how the dragon balls can grant one wish" asked piccolo.
"but the dragon balls on namek can grant three" said king kai.
Which surprised them all.
"so king kai how long it will take freeza to arrive to earth if he decided to come" asked goku.
"may be a year as he is other side of galaxy" said king kai.
"so need to train harder" said goku.
They all nodded, king kai didn't objected as he is observing goku and his friends they easily defeated giny force so king kai told them to go to yardrat to get train.
So goku and piccolo went first then tien and piccolo due to being motivated they all completed their training in six months so goku decided to test how strong is freeza