After finally exhausting all manner of traps and tricks on Angel Island, Knuckles makes his last stand at the entrance of the Master Emerald chamber in a one-on-one battle. Knuckles' attacks include the Spin Dash and gliding and falling on the player. If the player gets too close to Knuckles, he may use a two-punch combo to attack the player. If the player attempts to use the Spin Dash on Knuckles, he'll deflect the attack, causing the player to bounce back in the opposite direction. To defeat Knuckles, the player must Spin Jump on Knuckles' head while he is standing, or from beneath him, if he is gliding. Knuckles will also suffer damage if he falls on the player while they are using the Spin Dash. After eight hits, Knuckles will fall to the floor, defeated. Afterward, Knuckles will hear some commotion in the next room and run off.
Sonic the Hedgehog Pocket Adventure
Knuckles also appears as the boss of Aquatic Relix Zone zone in Sonic the Hedgehog Pocket Adventure. The battle mimics the one in the Hidden Palace Zone, and Knuckles performs the exact same moves and thus can be defeated in the same manner. Unlike the original battle, Knuckles only takes seven hits to defeat; afterwards Knuckles will fall to the ground and drop the purple Chaos Emerald. This is immediately followed by a short cut scene, wherein Sonic appears to try and give the emerald back, but Dr. Robotnik crashes into the area and steals it. With the area crumbling around them, Knuckles summons the last of his strength and delivers an uppercut to Sonic, sending the hedgehog flying into the next zone.
In their second duel during Sonic Pocket Adventure, after his defeat, and Dr. Robotnik's ambush, Knuckles might have punched Sonic out of the cave on purpose, indirectly helping him continue his pursuit against the doctor, and also possibly saving the hedgehog's life from the collapsing place.