Hyper Knuckles

Hyper Knuckles is a form similar to Super Knuckles in that it makes Sonic faster, invincible, requires fifty rings and makes Sonic glow. It also saps away rings at the same rate of one per second.

However, in addition to requiring the seven Chaos Emeralds it requires the seven Super Emeralds from Sonic 3 and Knuckles which are obtained by entering a large ring with all seven Chaos Emeralds. You are then warped to the Hidden Palace, where you are required to complete one of the Special Stages, which are the same Special Stages that you would get the regular Chaos Emeralds from in Sonic and Knuckles alone.

Knuckles glows the pink in this state, if he should touch a wall while gliding, it creates a wave that destroys all on screen enemies.

This character was only available in Sonic 3 and Knuckles and has not been in any game since.