In order to play Superboy, you need three things, cockiness, selfishness and a high opinion of yourself, although Johnathan Angel has all of those things, he also looks older then the other boys, which is a plus considering Superboy is the biggest on the team.
Elijah Wood, is a pretty fart smella'....I mean smart fella', so this role would be easy for him to do, he may need some Batman-esque type body armor (Batman, Batman Returns, Batman Forever {ugh} and Batman and Robin {ugh, ugh}) But after that and some comedy leasons, he'd be A-Okay as Robin.
Okay, what do we need here, okay some brown hair dye, some big shoes, a red and white suit, long hair and one Caulkin punk. If he can act stupid (he can, I know I've seen both Home Alone Movies) and naieve, we have Impulse. The dubmest thing on two legs would come together nice.
Alright, My favorite Villan in the DCU played by my favorite Wrestler in the WWF. Can't beat that, I think the Rock has just the right size and athletism to play the world's greatest Gunman Deathstroke, put a 44. Magnum with a scope in his hands and here comes Deathstroke. "Do ya' smell what Deathstroke is cookin'".