Super Saiyan Goku

Super Saiyan Goku is 's Final Smash in Super Smash Flash 2. Tapping into the vast reserves of his power, Goku transforms into his Super Saiyan (超サイヤ人, Sūpā Saiya-Jin) form. Goku's speed, strength and power are increased, and his hair and eye colors change. He can also skip his Super Saiyan 2 form to use the Super Saiyan 3 form, where he is powerful enough to use moves like the Ryū-ken and the True Kamehameha. Super Saiyan Goku is one of the many Final Forms in the game, meaning that he is a totally different character who has more powerful attacks than the regular Goku.

Upon transformation, Goku will cover his hands with both arms as the screen darkens and electricity crackles around him; then he will throw his arms to either side and yell as his hair turns blonde and his eyes green. His transformation has the second largest hitbox that is present during the Final Form transformations of many characters; it is a great yellow explosion in the shape of a flame that deals huge knockback and 18% damage to any opponents within range.

Super Saiyan Goku is one of the most powerful Final Forms in the game - his attacks rely more on brute power in damage and knockback, and he is completely invincible to close to all attacks - only some smash attacks and special moves causes him to flinch. In practical combat, it is close to impossible to KO an experienced fighter in Super Saiyan Goku's control, but if he happens to be Screen or Star KO'ed, for some reason there are sprites for said screen/star KO's.

Origin
This form originated in the manga series Dragon Ball. The transformation was first referred through numerous times during the Saiyan and Frieza sagas and finally made its appearance in chapter 317 of the manga titled Life or Death (生か死か, Sei ka Shi ka, lit. "Life or Death"). Goku was the first person ever shown on the manga to achieve it after witnessing his best friend Krillin's death at the hands of the villain Frieza, using this transformation to ultimately defeat the latter.

The transformation causes Goku's hair to stand on end and turn a golden color. His facial expression becomes sharpened, and the color of his irises turns to a bright emerald green. As a Super Saiyan, Goku's power level is 50 times greater than that of his normal form. Initially, the massive energies involved cause Goku's emotions to be stirred, making it difficult to remain calm. As a pure heart Saiyan, Goku becomes ruthless and overcome with rage. This is first demonstrated when Goku went from a calm, collected fighter to becoming a vengeful warrior, hellbent on avenging his fallen friend, Krillin, even at his own peril. With constant training, Goku eventually managed to control his emotions during the transformation and also achieve mightier forms of the transformation, like the Super Saiyan 3, which increases his power level 400 times greater than his normal form.

Trivia

 * Inside the data files of Super Smash Flash 2, there is unused an icon of Super Saiyan Goku for Classic Mode, he shares this trait with along with Wario Man, Kyūbi Naruto, Bankai Ichigo, and Crazy Hand.