Super Knuckles

Super Knuckles (スーパーナックルズ) is Knuckles' Super Form that is gained once all seven Chaos Emeralds are collected. The first appearance of Super Knuckles was in Sonic 3 & Knuckles and Knuckles in Sonic 2. Super Knuckles gains a pink aura, and appears to be bright pink due to coloration. Super Knuckles gains a bright pink pulse to his skin, but retains his basic physical form, unlike Super Sonic.

Abilities
While in super form Knuckles strength is greatly enhanced, as well as his speed and jumping etc. Like every other Sonic Character once he runs out of rings he loses super form.

Trivia

 * In Sonic Heroes Sonic uses some of his power to give Knuckles along with tails a light gold shield and enhanced strength, making him a Semi (or shielded) Super Knuckles.
 * Super Knuckles is one of the few Super Forms that didn't change to a golden glow. Super Knuckles changed to a pink glow instead.
 * Super Knuckles was also referenced in Sonic Chronicles. The Chaos Emeralds part of the journal stating Sonic, Shadow, Knuckles and a variety of people have been known to use the power of the 7 emeralds to go up to powered up versions of themselves.