My theory is that it could all just be misdirection. Arcade being able to blow up Mettle the way he did, as well as being able to transport all the kids to Murder World, makes me think Arcade is not acting alone. Perhaps he has help from someone like Norman Osborn .
It could be possible that Osborn implanted explosives inside Mettle's body while he was first recruiting Mettle for the Avengers Academy. Osborn did remove Mettle skin when he was first recruiting him. It's possible he could have injected him with nanoexplosives (hey this is my theory and I'm sticking to it).
As for the teleportation it could be that Arcade, with the help of Norman Osborn, recruited a villain with the power to teleport, like Exodus, to teleport the kids to Murder World.
Just a theory. Supposedly most of it will be explained next issue. Can't wait!