Sorry to disagree with you Hoshi, but in this instance Zodiac is right, Supersonic is completely Invincible as long as he has a healthy supply of Rings.
However, you forgot one tactic that Link has that can save the day for him... He can outlast Sonic's Super transformation with techniques like Nayru's Love, Mirror shield and Faries.
Once the Rings have run out, just catch Sonic with Din's Fire and it's all over.
Oni-Link's power comes from that mask which has dark powers. Oni-Link isn't temporary because he is far from invinicble. Super Sonic and Super Shadow are temporary because other wise you will never be able to be defeated. Oni-Link can't use the Master Sword because of the mask's dark powers and his items like bow and hookshot. Super Sonic can do lightspeed attack which Oni-Link wouldn't be able to stop of Super Sonic and Super Shadow would use Chaos Control and teleport Link and Dark Link into space like Ark where the die.
According to the story of The Legend of Zelda: Ocarina of Time, the chronologically earliest of the games, the Triforce was bestowed upon the world by the three goddesses Din, Nayru, and Farore, according to Hylian creation myth. It was said the actual creation of the Triforce occurred when the goddesses left the realm of Hyrule, at the exact point where they left, thus making the three triangles which form the Triforce fragments of the goddesses' power. Kept safe in the Temple of Light in a land parallel and reflective of the "normal" Hyrule, known as the Golden Land or Sacred Realm, the Triforce is the ultimate representation of all power, wisdom, courage and magic in Hyrule. The Triforce houses the essence of the gods, and it has been a subject of dispute whether or not the Triforce is an inanimate object that can't distinguish good from evil, or if it is a living entity, as depicted in the end of A Link to the Past.
Ganondorf Dragmire, a Gerudo thief and the sole male of their tribe at the time, heard of the legend of the Triforce and lusted after its power, primarily as a tool to subjugate the kingdom of Hyrule and expand his influence. Inadvertently aided by a young hero known as Link and the Hylian princess, Zelda, Ganondorf found his way into the Sacred Realm, but could only claim one fragment of the Triforce, the Triforce of Power, typically associated with the color Red and the goddess Din. The other two fragments split off and merged with Link, who received the Triforce of Courage, associated with green and Farore, and Zelda, who received the Triforce of Wisdom, associated with blue and Nayru. They were chosen by the Triforce itself because they represented these two segments of the Triforce above all others. Each of the three was marked with the mark of their Triforce on the back of one of their hands.
Eventually, Ganondorf was defeated and the power of the seven Hylian Sages (including Zelda herself) were used to seal him in the Sacred Realm. Regarding the three Triforce pieces, two were kept with Zelda and Link and the third Ganondorf kept. Link eventually left for a land known as Termina; but when he did, it is believed that his Triforce piece left him and split into eight fragments. In The Wind Waker, the newest incarnation of Link collects these eight Triforce shards. When Zelda died, her piece is also believed to have left her to be passed down through the generations of the Royal Family of Hyrule. Although Ganon struggled many times afterwards to rise to power once more, each time a new incarnation of Link and a new Princess Zelda are awakened to put him down and reseal or, eventually, destroy him.
In both A Link to the Past and The Legend of Zelda: The Wind Waker, it was revealed that one who touches the Triforce has all of their wishes come true; the Triforce reflects the heart of the one who touches it, whether good or evil. In A Link to the Past, Ganon exploited this power to corrupt The Golden Land, turning it into the Dark World, a realm of dark skies and evil creatures. In The Wind Waker, the king of Hyrule, Daphnes Nohansen Hyrule, wishes for Link and Zelda to have hope in defeating Ganondorf. The Triforce is also referred to as the "Golden Power" in The Legend of Zelda: A Link to the Past and could have something to do with the "Light Force" mentioned in The Legend of Zelda: The Minish Cap
Triforce is also the name of an arcade board developed as a joint-venture between Sega, Namco and Nintendo. The hardware is based on the Nintendo GameCube, but with more RAM (48MB instead of the Cube's 24). Sega ported its NAOMI Development Kit, originally developed for the Dreamcast game console, to the Triforce, making game development extremely simple. Among the games known to run on the Triforce hardware are F-Zero AX and Virtua Fighter 2002, both from Sega. In addition, a Mario Kart game for the Triforce, MarioKart Arcade GP, is currently being developed.