Don't kill me... Sonic Adventure 2, Finalhazard. Hear me out. (Major spoilers abound, but an entire post blacked out by a spoiler tag wouldn't have been that easy to read.)
The beast Shadow fought previously has merged itself with the space station, and is physically dragging it toward the planet in the hopes of setting off a chain reaction and destroying everything, to fulfill the revenge plan of a man dead for 50 years. So Sonic and Shadow both go Super, and race out to stop it.
As you fly through space (not "flat" sky/space flight like in Heroes, full 3D space flight), Sonic and Shadow are talking/yelling to eachother, with the other characters on the Space Station feeding you advice and support. Unlike SA1, you didn't directly collect rings, what would happen is that the character you weren't playing as would be supposedly collecting them while you were fighting, and if you were low on rings, you flew over or below the boss to "tag out," and the other would take over with the opposite of what you had within a set limit of 50 rings. Basically, for every second you lost a ring while fighting, the other was supposedly collecting one. This means that there's no real way to "tag out," and not have enough rings to tag back again (short of an attack by FH intervening), since you'll end up with either an equal or greater amount of rings.
Anyway, Finalhazard at first starts shooting a few red bubbles at you, akin to his original ground attack in his Biolizard form. You wail on the puffed-up/inflamed spot in his armor (yeah, it's mocked a lot, but you already trashed his blatant power source hit point previously, and this lets the point appear in different places), then tag over to the other fighter. Finalhazard's attacks increase, growing to a spherical shield of red bubbles flinging at an increased rate, and double rotating lasers. Meanwhile, other plot points are being set up, including that Shadow is having trouble keeping his Super form like Sonic, and late into the fight, depending on if you're Sonic at the right time, he has a revelation that Sonic might be the true ultimate lifeform (either via legend, or by Gerald Robotnik's hand, explaining why Shadow the prototype was a hedgehog too). It's an interesting point that the Sonic games have since abandoned in favor of keeping Shadow's "I'm the best!" ego.
Once you've destroyed him, Sonic and Shadow both team up to teleport the station back into place, but Shadow doesn't teleport along with the station (whether he used his energy to help save Sonic or just gave up, it's uncertain), and he falls into the atmosphere and disappears. Sonic and Co. have a bit of a somber moment, with even Eggman a bit concerned by what lengths his grandfather went to to gain revenge. (Eggman in his better-written moments isn't someone who wants to destroy the world, just rule it.) A nice somber note unfortunately ruined when Sega realized how popular Shadow was. (To be fair, I like the design, but it was just too much of a death cheat, and him dying will never matter again.)
Back on the bossfight, one of the details a lot of people don't see is that, unlike Perfect Chaos or Metal Overlord/Madness, rings aren't your only deadline. I believe you only get 5 minutes, and as it gets closer to the time limit, the screen starts getting redder as you enter the atmosphere, with particles burning up in front of you. Finally, as you reach the last few seconds, the support cast on the space station start screaming for you to give up and get out of there. I can't remember for certain, but I think the screen whites out. The effect is excellent, but again, most people either die from running out of rings or beat him in time.