SPOILERS FOR SONIC THE HEDGEHOG 3 BC I WATCHED THE MOVIE!

Everyone was on the spaceship with Sonic and Shadow using the emeralds to make them super Saiyan (whatever it's called). Sonic couldn't take it anymore and passed back to normal in space, going unconscious and about to crash into Earth. Tails tried to sue the last ring to save him but unfortunately he also goes unconscious while going into the Earth's orbit. Knuckles grabs you and you both get Tails and Sonic and use the ring to go to a vast field somewhere safe. Shadow and Robotnik are still in the space ship which was now going to explode into flames soon, both of them knowing that and sacrificing themselves. In the sky, you could see a burst of like an explosion in the sky in the distance, soon enough looking like a small galaxy in the distance due to the amount of chaos energy and whole thing with the ship. Presumably, both Shadow and Robotnik had sacrificed themsleves for the sake of Earth as you saw all that unfold in the distance.

((Note from the creator:))

((I refuse to believe the two are dead and I hold onto H O P E that they are alive. But yes in the end they did die... Or that's what everyone thinks but yeah its like a debate. I want to believe they're alive but in the movie they're shown to be "dead"))