Super transformation refers to the ability of various characters in the Sonic franchise to use powerful items to achieve a more powerful state, usually accompanied by visual changes. The concept has been used in virtually all Sonic media since the debut of Sonic's powered-up state Super Sonic in Sonic the Hedgehog 2.
In Sonic 2, Sonic 3/Sonic & Knuckles, Sonic the Hedgehog 4, Sonic Colours, and Sonic Generations with the skill enabled, transformation to Super Sonic, or (albeit less frequently) one of the other characters' super forms, may be used at any time once the character has collected all seven Chaos Emeralds and has at least 50 rings. In these games, rings are lost at a rate of approximately 1 per second (actually 60 rings every 61 seconds), and upon reaching 0 rings, the character reverts to normal.
Most recent games feature super transformation as more of a plot point rather than a regular gameplay mechanic. In these cases, it only appears towards the end of the game, such as in Sonic Adventure, and often associated with a final battle in space. This trend is frequently cited as having been started by the Doomsday Zone in Sonic & Knuckles, despite the fact that said game did allow Super/Hyper forms in regular levels too.
Super states and other transformations are generally much faster than the character's normal form, and are also invincible to many enemies. However, they are still susceptible to being crushed, falling down a bottomless pit, or drowning, as well as certain other things. In addition certain games offer alternatives to Super States, or allow them to be powered up further.
Multiple characters have been shown to be able to transform into a Super state. Moreover, other forms besides Super have been revealed in various games and other media. The following list is sorted by the order in which characters were revealed to have Super or other states and then by the order in which said states appeared.
Sonic the Hedgehog was first shown to be able to transform in the game Sonic the Hedgehog 2. Since then, he has become the most frequent user of super transformation, and has the most transformations in the series. When He turns Super, his eyes turn glowing red and he is a lot stronger.
From Sonic 2 onward, Sonic has the ability to transform into Super Sonic upon collecting all 7 Chaos Emeralds and at least 50 rings. In this form, Sonic takes on a golden, glowing appearance, and he invincible to many obstacles to which Sonic is normally susceptible. Super Sonic is the most recurring super transformation, appearing in nearly every game in which Sonic does, including cameos.
Only appearing in the Sonic X TV series, Dark Super Sonic is a more anger-filled version of Super Sonic powered by fake Chaos Emeralds. He becomes completely black except his gloves and shoes. Sonic powered down when his rage subsided, and this Super State has not been seen since.
Only appearing in Sonic 3 & Knuckles, Hyper Sonic is a more powerful form of Super Sonic, available once Sonic collects the 7 Super Emeralds. Visually, his changing colours encompass not only yellow but rather the various hues of the 7 Emeralds, and he moves so quickly that mirages of himself appear behind him. He can perform a type of double jump, whereby pressing the jump button again causes him to shoot off in the direction being held on the controller; this allows him to reach places that he cannot when Super (or normal). He can also breathe underwater, again a trait that Super Sonic does not possess. Despite having superior powers, he loses rings at the same rate as Super Sonic.
At the end of Sonic and the Secret Rings, Sonic becomes Darkspine Sonic upon absorbing the power of 3 of the 7 World Rings. He is darker and exhibits various other physical changes. He can fly, but he is not invincible. Sonic's rings are not consumed by this state.
During the battle against the Dark Queen at the end of Sonic and the Black Knight, Caliburn absorbs the Sacred Swords of the Knights of the Round Table to become Excalibur. This transformation encases Sonic in a suit of spontaneously-generated gold-plated chain-mail, although he remains his normal blue self beneath the armour. As such, Excalibur Sonic might more properly be considered a super transformation of Caliburn the Sword than of the hedgehog himself.
Miles "Tails" Prower was first shown to be able to transform in the game Sonic 3 & Knuckles.
Appearing only in Sonic 3 & Knuckles, Super Tails is faster, glows golden, has the same invincibility as Super Sonic, and is surrounded by golden Flickies, which will attack any enemies on-screen. Tails must obtain all 7 Super Emeralds (and, therefore, also all seven Chaos Emeralds) and at least 50 rings to be able to assume this form: having all seven Chaos Emeralds alone does not give him any extra powers.
Interestingly, in the May 17 1994 prototype of Sonic 3, Super Tails does not have Flickies, and a second form, analogous to what would be "Hyper Tails", does.
In Archie’s comic series Sonic the Hedgehog, this form is referred to as Hyper Tails. His Super form was named Turbo Tails; see below.
A newer version appears in Sonic Heroes. Playing as Team Super, Tails is enclosed in a golden sphere and has the same abilities as Super Sonic, including invincibility, flight, and Sonic's "light attack". This form, however, is not accompanied by Flickies.
Upon collecting the Chaos Emeralds, Knuckles can become Super Knuckles. Knuckles glows with a pink energy field and gains an enhanced gliding ability, in addition to the standard Super State effects.
A newer version appears in Sonic Heroes as a part of "Team Super", in which he simply appears to be surrounded by a golden sphere. Knuckles gains the traditional Super State effects, in addition to "Light Attack" and a much more powerful combo move.
In the American Sonic the Hedgehog comic series, this state was renamed "Hyper Knuckles". It was thought to have been retconned back into "Super Knuckles", but the comic's current writer says this was a misprint.
By collecting all of the Chaos Emeralds and Super Emeralds, Knuckles can become Hyper Knuckles. Like Hyper Sonic, he leaves afterimages and is unable to drown. He can also destroy all on-screen badniks by gliding into a wall: this creates a screen-wide shock-wave that causes badniks to explode.
For his All-Star move in Sonic & Sega All-Stars Racing, Knuckles used the Master Emerald to achieve a super transformation, becoming the second character in the games to do so. The move, simply dubbed "Emerald Power", transforms Knuckles in to his Sonic Heroes Super State, but with a glowing green aura instead of a yellow one. He also leaves a bright green energy trail when he flies. His attack is a super charged Hammer Punch, which causes earthquakes strong enough to disorient every player ahead of him.
For many years the only antagonistic Super form ever shown in the games, Mecha Sonic's transformation was the first one to draw power from the Master Emerald, and the only instance of a non-biological character executing a golden, glowy transformation. Super Mecha Sonic serves as Knuckles' final boss in Sonic & Knuckles, after which the robot is destroyed.
With the aid of the Chaos Emeralds, Shadow can become Super Shadow. He generally just becomes a lemon cream color, and has mostly has the same abilities as Super Sonic. His Chaos Emerald abilities are all enhanced and can be used at any time while he is Super.
Like Knuckles and Shadow, Blaze the Cat was also given a transformation in her debut playable appearance.
With the aid of the Sol Emeralds Blaze can become Burning Blaze. Despite the different name, the form is most similar to other Super states. Blaze is the first character whose clothes change color when transformed.
Silver the Hedgehog continues the trend of prominent story characters going super in their debut playable appearance.
Silver's Super State, Super Silver is the only Super State to not have been shown to be accessed by any items of power. Instead, he was given the power to transform by Super Sonic. He has been shown to have enhanced psychokinesis, and the ability to fly, and a new abilty called the Shield of Light.
Ix's Super form is in fact the only time we get to see the Imperator as a recognisable echidna, divested of his voluminous robes and head-dress. Super Ix has glowing cyan eyes and platinum-white fur. He fights against Super Sonic, his special move being Overload.