Super Saiyan 4 is the fourth and final form of Super Saiyan, making it's official anime debut in the episode "Goku's Ascension".
The Super Saiyan 4 form's general appearance is that the saiyan is covered in reddish fur, saiyan gains his eyebrows again, hair is extended (Not nearly as long as Super Saiyan 3, though), the saiyan gains a reddish fur tail, and upperwear completely disappears.
In this form, the saiyan's personality becomes that of a great ape, sometimes brash, but is able to control his/her actions while in this state.
Battling Baby Edit
Goku achieves Super Saiyan 4 out of Pan's crying that he may never return to normal again. After achieving it, Goku orders Hercule to take care of Pan, while he proceeds to fight Baby Vegeta. Baby sense him coming, and after a conversation with Baby-possessed Bulma, Goku and Baby fight. Goku has the upper hand in this fight, so Baby uses Blutz Waves to transform himself into a golden great ape. Still, Goku has the advantage in strength, so Baby uses more Blutz Waves to recover. Goku friends were freed from Baby's control, and proceeded to assist Goku, but he insists that they don't fight, as they are not strong enough. Goku, using his Super Saiyan 4 strength, absorbs, Baby's Revenge Death Ball Final. He then uses a kamehameha to blast off Baby's tail. Baby decides to leave Vegeta's body, and the planet, but Goku fires another kamehameha, blasting Baby into the sun and ending Baby's reign of terror.
Super 17, the Ultimate Android Edit
Goku uses this form on Super 17 when he realizes he cannot combat him as a Super Saiyan. He then explains the form to 17 and Dr. Myuu. He then proceeds to destroy Super 17 with a barrage of energy blasts. But this doesn't work. He then proceeds with a marathon of other attacks, including the kamehameha. Goku realizes that Super 17 is absorbing his attacks like Android 19 in Dragon Ball Z. He then charges up another kamehameha, but remembers that it won't work, he'll just absorb it. When battered and broken, Super 17 prepares a finshing attack for Goku. Goku then gets out of the way, and proceeds to kill himself and take the android with him. But 17 puts up a shield that saves his and Goku's life, but he reverts to his base in the process. Goku then destroys 17 with Super Dragon Fist and three kamehamehas.
The Shadow Dragons Edit
Goku uses Super Saiyan 4 to combat Rage Shenron, but this proves futile with the latter being electrocuted. He uses this form on Naturon Shenron, both in mole, Pan, and normal forms. Goku while in this form destroys Naturon Shenron. He uses this form again to battle with Nuova Shenron, who revealed his true form. He battles the dragon in this form for a good while, until Eis Shenron steps in. He reveals that while he was elsewhere, he beat up Pan and left her lying in the streets. Goku, angered by this , proceeds to Eis Shenron intstead, claiming he can take him out in five seconds. Though he would have, Goku is not true to his word because Eis uses Pan as a shield. Goku then returns the favor, and Eis uses Nuova as a shield so he can freeze Goku again. however, Goku breaks free from his icy confines. Eis then begs Goku not to kill him and Eis blinds Goku. Goku then punches a hole in Eis, and uses Dragon Fist to kill him once and for all.
The Strongest Shadow Dragon Edit
Nuova gives Goku an antidote for his eyesight. A new dragon then kills Nuova from behind. Goku then proceeds to fight the dragon, but this dragon is far too strong for Goku to handle. He reverts to his base form. After taking the the powers of Gohan, Goten, and Trunks, he transforms to Super Saiyan 4 again. Now stronger than ever, Goku easliy combats Syn Shenron on his own. When Syn gets desperate, he absorbs the nearby dragon balls, achieving his ultimate form, Omega Shenron
The Ultimate Shadow Dragon Edit
With Syn having achieved his ultimate form, Omega Shenron, he uses Gigantic Blaze to blow everyone except Goku away. He then proceeds to battle with Omega Shenron, with Omega displaying the abilities of all the Shadow Dragons. Sometime during the fight, Goku regains his eyesight. Still, he is not powerful enough to defeat Omega Shenron. When desperate times call for desperate measures, he begins a kamikaze, but Vegeta steps in. With Bulma's help, he achieves Super Saiyan 4, but even with two Super Saiyan 4s, Omega Shenron is superior. So Goku and Vegeta fuse, making Super Saiyan 4 Gogeta. Gogeta is able to completely overpower Omega in this state, so Omega uses Negative Karma Ball to destroy the Earth. Gogeta floods the ball with his life force and kicks it away, lifting the dark energy enveloping the Earth. Gogeta then uses Big Bang Kamehameha. Omega reverts to Syn Shenron, and just when Gogeta is about to use it again, he defuses. After hit after hit after hit, Goku and Vegeta use the Afterimage Technique to confuse Omega, and fuse. But it doesn't work. Omega allows them to fuse again, knowing that Goku is far too weak, and he reverts to his base. Goku later develops the Universal Spirit Bomb to kill Omega, ending the threat of the Shadow Dragons.