Goku has the exact same appearance just like how he looked in the original manga.
Goku is a man of decent height (little over 6 feet) and possess a very muscular physique that was attained from years of hard training. He has spiky black hair in the shape of a palm tree, which will never change due to his saiyan genetics. Like most saiyans, Goku has black eyes and has a somewhat tanned complexion to his skin.
In terms of facial features, Goku is usually seen with a joyful expression on his character. Thus he will usually be seen smiling or laughing, though his looks will harden if the situation calls for it.
Gokū is shown to be a cheerful, energetic, and determined individual. Known for his love of competitions, Goku enjoys training every single day in order to improve his own strength.
Goku is a true family man at heart, and does whatever he can to help them out whenever possible. This selfless attitude also extends to his friends and enemies alike, in order to help them out and to give the villains a chance at redemption.
Upon being absorbed by Majin Buu, Goku and the others gave Buu a everlasting influence on his character. These new sensations includes a love for the Earth, the need to train, and a sense of being good now (reviving the killed victims, helping out the universe at times, etc). Thus, the positiveness of Goku's character has helped transform Buu into the being he is today.
During Age 764 in preparation for the android invasion within three years, Goku is seen having a picnic with his family. After finish telling his family that they can relax due to the android invasion being far away in time, they were subsequently ambushed by Cooler and his armored squadron. As certain events unfold, Goku is later seen to be slightly injured (but as a Super Saiyan now) while facing a battered Cooler near a waterfall. When Cooler finishes his Augmentation Transformation, Goku notes he his much stronger than before, with Cooler taking advantage of Goku's dropped guard by instantly headbutting him. Now bleeding from his forehead, Goku attempts to blast Cooler with a full-powered energy wave, but Cooler dodges it and knocks him into the ground. Before he could get out of his crater, Goku is hit by Cooler's Death Wave which creates a massive fissure in the ground. Once Cooler notes he is tough, Goku flies out of the crater sporting a new war wound. After Cooler finishes praising Goku's endurance (and bolstering about his own supremacy), Goku tells him that he hasn't used his full power yet and that Cooler shouldn't underestimate him. When Cooler tells him to bring it, Goku accesses his true strength and charges at Cooler which results in a flurry exchange of blows. As time goes by, Goku is next seen dodging a massive explosion, but is caught off-guard by a remote-detonating energy blast from Cooler. Luckily for Goku, his reflexes were fast enough to initiate the instant transmission in time, thus avoiding the subsequent explosion and appearing right behind Cooler. Goku then immediately blasts Cooler in the back with a powerful energy wave, followed by a discharge of many ki blasts. As Goku waits for the smoke to clear, Cooler emerges and is heavily damaged and enraged by Goku's power. When Goku tells Cooler to give up due to his injuries and diminished power, Cooler goes into a heated frenzy before flying in the air and charging up his Supernova. When Cooler finally release the sphere of destruction, Goku immediately fires his Kamehameha which over powers Cooler's own energy attack. At the receiving end of the beam struggle, Cooler is thrown straight into the sun, thus he burns alive in a raging inferno. With the threat finally over, Goku (who is back in his base form) is seen talking to his friends and son about their victory, as Vegeta spies on them from afar.
In Age 767 between the 20 and 26 of May, Goku ventured with Vegeta and the others to "New Planet Vegeta" to allow Vegeta to become king there, and to defeat this mysterious "Legendary Super Saiyan". As certain events unfold, Broly transforms into his Legendary Super Saiyan form and proceeded to defeat everyone as time went along. After Broly had killed his own father, Goku was the only one still standing as the comet was getting closer and closer. With little left on their plates, Piccolo proposes the Spirit Bomb, which Goku states that he needs a distraction for it to work. Gohan takes up his father's call for help and dashes straight for Broly, as Vegeta laments that all is hopeless. As Goku is collecting energy from across the solar system, he attains even more energy from Piccolo, U12 Trunks, Krillin, and even Vegeta. Once Gohan is saved from Oolong's distraction, Goku launches the Spirit Bomb at Broly, who crashes into the comet that results in a violent explosion.Relieved that his energy disappeared and the danger of the comet has passed, Goku is asked by Krillin that Cell should be easy to defeat. Goku simply states that while Broly was powerful, he doesn't even come close to Cell in terms of how to fight or to use his true strength. Feeling like he has rested enough, Goku teleports everyone back into Earth to rest some more, and to prepare for the Cell Games.
In Age 774 between April 20th and the 7th of May, Goku senses Broly's presence on Earth while dining with King Kai on his planet. Despite telling Goku to make no hasty moves, King Kai does say that the authorities are underway of making the necessary actions to fight against this universal threat. Goku merely states that they don't have enough time, and transforms into a Super Saiyan 3. When King Kai says that Goku can't leave for more than a second, Goku agrees and says that it is just a little "training", nothing more.While charging up his Kamehameha, Goku waits for the right time to teleport into the battle. Upon seeing the moment to intervene, Goku teleports to Earth and sends his blast at Broly along with Gohan's and Vegeta. As Broly is flying to the sun, Goku powers down and immediately teleports away to avoid detection, though Gohan believes he has seen him there. Broly is then fried inside of the sun, thus ending the life of the Legendary Super Saiyan for good.
Just like his Universe 18 counterpart in Age 774, Goku battles the threat of Majin Buu exactly up until the point when Vegetto defuses inside of Buu. When Goku and Vegeta (both are Super Saiyans) confront Buu inside of his own body after freeing the absorbed, Vegeta attempts to dislocate Fat Buu from Super Buu's system. And this is where the change is made from Universe 18!
As Vegeta was about to tear apart Fat Buu from Super Buu's body, Super Buu decides to act (instead of begging like his Universe 18 counterpart) by desperately attempting to absorb Vegeta. Unable to help Vegeta as he is being consumed by Buu's body, Goku manages to flee from the same absorption mechanism that Buu is utilizing, as the latter is laughing with drunken glee while slowly transforming.
After Vegeta has been successfully absorbed, Super Buu completes his transformation as Goku wonders what has happened. Goku then suddenly hears from Buu that he has moved Goku away from his organ that keeps his absorbed victims as he materializes a physical body. After showing off his new form to Goku after stating he doesn't want any more trouble with his absorbed victims, Buu then states that he wants to defeat Goku since he owes Vegeta the satisfaction of beating him. After listening to Buu that he wont escape this place while this will also being his last fight, Goku realizes that he cannot teleport from this fight (he cannot sense any energy outside of Buu's body due to the walls) and that the walls are indeed too strong for him to break. With no other options left, Goku instantly becomes a Super Saiyan 3 and declares that he will finish things here once and for all. This declaration makes Buu smile with anticipation.
Not one to waste any time, Goku throws a powerful right kick to Buu, though he manages to block it. Goku then decides to throw a strong left jab at Buu, but he dodges it as well before headbutting Goku and attempting to kick him, but Goku manages to dodge it at the last second. Telling Goku that running away is useless, Buu fires a powerful energy wave at Goku. Goku narrowly manages to dodge the blast, which causes a massive explosion upon hitting the fleshy walls of Buu. Falling onto his knees from the explosion's aftershock and slight fatigue, Goku is instantly attacked by Buu while asking if Goku is "tired already". Before Buu's punch could connect with Goku's back, Goku uses his Instant Transmission to dodge it, followed by a Kamehameha to severely injure Buu. As Goku lowers his hands to see if he had killed Buu, Buu suddenly regenerates and creates a smokescreen while being mad now. Before Goku could finish saying that a smokescreen will not be enough to stop him, Goku is suddenly attacked by a barrage of energy blasts. After barely dodging them all, Goku is instantly elbowed in the chin, followed by being violently thrown by his hair. Managing to catch his balance upon landing on the wall, Goku was about to be attacked by Buu again before they both realize that their entire surroundings are being warped. As Buu comments that he just cannot be left alone, Goku begins to assault Buu in a explosive barrage of punches and kicks. Barely able to block Goku's attacks as Kibitoshin wails on him in the real world, Super Buu suddenly dissolves into the wall to take care of his unwanted hindrance.
Noting that Buu is now gone, Goku then decides to take advantage of his time being alone. Believing that the Earth shouldn't be at risk from his attack, Goku takes a certain stance and begins to power up to his absolute capacity, and beyond. When Super Buu finally materializes from his outside ordeal, Goku has finally gathered enough power to utilize a incredibly strong Super Explosive Wave, thus greatly scaring Buu before being destroyed. In the real world, Buu's entire body explodes which throws away Dende, Hercule, and even Kibitoshin.
As the entire explosion settles down, Goku regains his original form before he suddenly powers down back into base form as he rapidly falls to the Earth. Congratulating Goku as he regenerates, Buu comments that if that attack was used outside of his body, both the Earth and the Solar System would have been utterly destroyed (including Buu as well). Upon finishing his regeneration and appearing before Goku, Buu states it is a beautiful finale before extending his left hand on Goku's head for absorption. Completely exhausted while kneeling against a rock for support, Gokū cannot do anything as Buu slowly absorbs him into his new permanent home. While getting absorbed, Buu also reabsorbs his other victims (Gohan, Piccolo, Goten, and Trunks) to become stronger than ever before. With his transformation complete, Goku is then shown to be inside of a pod, completely unconscious along with Buu's other victims.
Despite being gone now, Goku's legacy continues to live on since his essence has transformed Buu from a hardened killer into a life-form that has softened up to life as time went on.
Multiverse Tournament (First Round)
Although Goku does not appear himself, he is briefly mentioned when Zen Buu talks to Universe 18 Goku that he has absorbed a version of himself as well. This news somewhats unnerves U18 Goku to some extent as Buu talks to himself that all beings with power in his universe is now in him.
Goku is just as strong as his counterpart in Universe 18 at this point in time.
In the canon anime and manga, Goku expressed his belief that he could not defeat Super Buu (no absorption's) no matter what he and Vegeta did when they were trapped inside of Buu's body. However, DBM changed this notion by a significant amount.
During his final battle against Super Buu with Vegeta absorbed, Goku surprisingly managed to hold himself throughout their skirmish as a Super Saiyan 3. When Buu subsequently leaves to take care of Kibitoshin, Goku manages to power up to the point he was powerful enough to almost obliterate Majin Buu from the inside-out. While he does fail, Buu does commend his efforts and states that if he used that attack outside of his body, Buu might have been killed while destroying Earth and the entire Solar System in the process.
Ultimately, Goku's collective power has so far been officially shown to be the second (third if you count Gotenks) best absorption for Buu in terms of power scaling. Gohan is still Buu's greatest absorption revealed so far.
Flight: The ability to levitate by manipulating one's ki.
Ki Blast: A ball of energy that can have devastating effects. Goku used a full-powered energy wave version twice against Cooler in Age 764, as well as a flurry of smaller blasts against him.
Kamehameha: Goku's signature move. Used to kill Cooler and to attack Super Buu.
Instant Transmission: A powerful ability to teleport anywhere long as ki is able to be sensed.. Leaned during his time on Planet Yardrat.
Instant Kamehameha: A combination of Instant Transmission and Kamehameha. Used against Super Buu and Broly during their final battle in Age 774.
Super Explosive Wave: A powerful omni-directional attack. Goku used this as his final trump card against Majin Buu.
Spirit Bomb: Goku's most powerful attack. Used against Broly during his original confrontation on New Planet Vegeta.
A powerful saiyan form that multiplies one's capabilites drastically. Goku is shown using this form multiple times, with his final usage being against Super Buu before he absorbed Vegeta.
Super Saiyan 2
Despite Goku having this form, he was never shown to be using it in the comic yet.
Super Saiyan 3
Goku's most powerful transformation. Goku utilized this form during Broly's second coming and during his final battle against Majin Buu.
- Although it hasn't been stated yet, but is could be possible that Goku and the others are now permanently a part of Buu now since they have been absorbed for 20 years. Whether it true or not remains to be seen.