The Energon Pub

[Rodimus Prime]

So, Unicron arrives at Earth, ready to devour it. Superman decides to take the initiative, and flies out into space to confront the menace before anyone else, even the Autobots, can react. Can he cause enough damage to stop the planet eater, or will Unicron be able to destroy him or at least incapacitate him? Would Unicron know about/have any Kryptonite?

[d_sel1]

Would Unicron know about/have any Kryptonite?

I am only focusing on the last part of this question right now. It depends on three things
1. if Unicron passes by the some of the remnants (preferably a large chunks near Krypton's orbit) of Krypton: If Unicron knows or does not know about Krypton, it might not matter. Maybe I am wrong, but isn't Kryptonite kinda rare.
2. Is the chunks of Kryptonite that Unicron passes by big enough for Unicron to bother with eating. Would Unicron bother with consuming "finger food" sized chunks of Kryptonite. How about "crumb sized" or "snorting sized?" Of course, Unicron could get a covered Kryptonite dust or even a Kryptonite "splinter."
3. We also need to know more about Unicron's digestive and grooming habits. If Unicron digestive system alters the molecular structure of Kryptonite too much, then it is useless. Useless if Unicron bathes regularly, he may lose Kryptonite dust.

So, Unicron arrives at Earth, ready to devour it. Superman decides to take the initiative, and flies out into space to confront the menace before anyone else, even the Autobots, can react. Can he cause enough damage to stop the planet eater, or will Unicron be able to destroy him or at least incapacitate him?

The rest of question depends on which era of Superman? The early "Pre-crisis Superman" could destroy a solar system by sneezing, so Unicron could be destroyed without Superman even trying. However "Post-crisis," I do not know at the moment.

[snavej]

In order to travel quickly from star to star, Unicron must have very good hyperdrive technology. He could use this to teleport Superman into a black hole or some other extreme environment. Unicron wins.