Pochacamac was an elderly echidna who was the father of Tikal and the leader of the ancient tribe of Echidnas. Over 8000 years ago, the Drakon Empire came to ancient Mobius and took over the sacred Echidna emerald mines in an attempt to find a suitable vessel for their unstable new energy source. This 'Chaos Energy' was insecure, but the Echidnas' emeralds were found to be the ideal container. Pochacamac then ordered his men to recapture the emeralds to save the galaxy from the Drakons. The Drakon Empire then waged war on the Echidnas.
Using an advanced form of Chaos Conttol, he and Tikal successfully transported Sonic into the distant past. Sonic assisted Knuckles in the capture of a Drakon Prosecutor so Pochacamac could negotiate for a peaceful compromise, but the plan went sour when the Drakons made an unexpected advance. In the resulting battle, the Chaos Emeralds were struck by a stray energy beam, driving the already unstable energy past its limit and dousing the captured Drakon Prosecutor, leading to the creation of Chaos.
Tikal says this is only the beginning of the Great War, and the Echidnas begin a futile attack on Chaos. Using the power of the Emeralds, Pochacamac sent Sonic back to the future time with the a portion of Chaos' power, weakening the creature enough to seal it away. When the battle was won, Pochacamac, Tikal, and Knuckles thought about the beginning of a war that would determine what would happen to the Echidnas. Although they knew Knuckles would somehow survive for the next 8000 years,they realized that everything else was lost.
Later on, Pochacamac saw that the Echidnas were losing the war, so he decide that the Echidnas need a guardian that will protect the Floating Island and the emeralds forever. In order to make Knuckles an eternal guardian, Pochacamac made a deal with the God of Death, Vichama. He said that he would give him a passage onto the mortal plane, in exchange for helping create the Guardian Emerald. This meant that while Vichama remained, Knuckles would be continuously resurrected and the Chaos Emeralds would always be guarded. Unfortunately, Vichama went on to slaughter thousands of echidnas. Instead of banishing him (and losing Knuckles' immortality), Pochacamac imprisoned Vichama's spirit in an echida corpse and then sealed that corpse in suspended animation. Vichama's great temple was torn down and the Temple of Tikal placed over it.
Pachacamac is portrayed as a much more pleasant person than in the games, in a sharp contrast to how other characters, such as Chaos, are portrayed as eviler.
Having lived so long ago, he's likely dead.
In games he's called "Pachacamac" not "Pochacamac".