Hyper Knuckles (Sonic 3 & Knuckles)

If you are playing Sonic & Knuckles locked-on with Sonic the Hedgehog 3, collecting all 7 Super Emeralds (which are obtained by re-entering Special Stages with the 7 Chaos Emeralds) as Knuckles unlocks Hyper Knuckles. Similar to Super Sonic, Hyper Knuckles is invincible, faster, and jumps higher. He also has a unique ability: when gliding, he can perform a powerful 'wall-destroying' punch that creates a small explosion, damaging enemies and breaking certain blocks. Like Super Sonic, Hyper Knuckles drains rings, so careful management is necessary. This form makes Knuckles an unstoppable force, capable of tearing through levels and bosses with ease.