Final Boss (Knuckles)
As Knuckles, you'll zip up to a teleporter from Hidden Palace, and catch three rings when you get up there. Keep them close, as they're the only rings you get in this final battle arena in the skies. Note that Angel Island is airborne in the background, but it's unstable without the Master Emerald and will begin to plummet unless Knuckles can retrieve it, by completing this boss (and having collected all the Chaos Emeralds too, by the way). Almost immediately, the Eggrobo that's been following you around reappears once again from the right, and he's got that grabbing attachment on the Eggmobile. He'll slowly move towards you and the attachment rises and falls to stay in line with your vertical position, as you jump. There's no way of avoiding it (or any point), so just allow him to catch you. From there, Eggrobo will take you across to the right where the screen scrolls to reveal the Mecha Sonic, accompanied by that awesome piece of final boss music from Sonic 3. Sonic didn't destroy the Mecha when he had the chance, during his run through this zone, and now it's the only thing standing in Knuckles' way to the Master Emerald. The Mecha spins into a ball and jumps to the middle, then dashes along the floor and upwards, trying to finish Knuckles off while he's being held in the grabber. Doesn't work out though, and Knuckles automatically glides his arse out of there just in the nick of time, leaving the Eggrobo badnik to take the full force of the attack instead, which finally finished him off. Would have been nice for Knuckles to settle that score, himself, but whatever. From then on, you fight the Mecha in exactly the same way Sonic fought him in his third boss fight, so please read that section just above for more info... Then come back down here again.
Beaten him? Good. He collapses again, but it's not over yet. As the music for Doomsday Zone hits, his eyes light up again like the Terminator, and he'll dash backwards to the right. As the screen scrolls along, you'll see the Master Emerald sitting on the far right hand side. But look! Mecha Sonic hops on top of it and uses it to charge himself up! Knuckles dashes over but he's too late, and Mecha launches into the air, glowing with pure emerald power. This time, you'll have to fight "Super Mecha Sonic"! He's tough, but working strictly to a set pattern, you should be able to survive.
First of all, go and stand right in front of the Master Emerald, leaving a bit of space away from the edge of the screen. The super powered robot will zip back and forth across the top of the screen for a bit before eventually staying in the top left corner. From there, he'll either drop down and charge at you, (which is a very sudden attack, so be prepared to jump over him when he comes round), or he'll stop and use up all his energy to fire three large flashing projectiles at you from his stomach. If he charges, then he'll fly straight back up afterwards and repeat, without needing to go back to the Master Emerald. You'll know he's about to fire the three projectiles when he looks up and leans back a little bit, while staying in the air. What I usually do at this point is begin to charge up a spin dash facing left, but don't release it just yet. Instead, wait for the first projectile to be launched, and heading towards you. While it's on its way, release the spin dash, and you'll go all the way to the left side of the arena. The second projectile will aim at you while you're moving, so it'll miss you completely, and for the third one, you'll just need to jump over it.
After that, Mecha Sonic will be drained of his super power and will need to retreat back to the Master Emerald to recharge. Your opportunity to attack is when he's in this weakened state. He'll return to normal in the air, and then drop down. Before he lands, get close to him and then jump up to mark your first hit. Just make sure you're facing him and don't touch his spikes. He'll begin spinning when he lands and then shoot off back to the Emerald. Charge up another spin dash, this time to the right, and wait about a second or so, and then release. If you've timed it just right, you'll hopefully hit him from behind after he's stopped spinning, but just before he jumps up on the emerald. This can be tough at first, and perhaps a safer, though less effective strategy would be to stay near the Master Emerald, dodge the projectiles from there, and then intercept him when he comes to recharge. There are a number of strategies you could employ for this phase, but you don't get many clear opportunities to hit him, so experiment to see what works best for you, if you've got enough lives to spare that is.
After six hits in that first phase, he'll ditch those attacks and try something else. After his next charge-up, instead of zipping around like a crazed monkey, he'll calmly float around the top of the arena, but following your movements as you walk across the floor. At regular intervals, he'll produce eight small ring-like objects that fire outwards at all directions, and fairly quickly too. If you're experienced, you might be able to stand roughly where you know you'll squeeze into the gaps between them, but everyone else should stay far away from him during this phase. Not too far though, because after every one or two blasts of harmful rings, the super powers start acting up a bit, and Mecha Sonic briefly reverts to his regular self, and drops a little bit towards the ground before floating back up and resuming the super form again. This is your chance to land the final two blows to finish him off once and for all! He'll start exploding and so will the ground, for some reason. The screen turns to white and congratulations! You've completed Knuckles' adventure through S&K. Details of his ending sequence will be added to the Stages and Story page.