Trying to stick to the good-guy, bad-guy formula here...
- Bugs Bunny as Superman. Plain and simple.
- Daffy Duck as Batman. Batman more than anyone else is Superman's opposite in the JLA, the flipside of his coin. Bugs and Daffy occupy the same slots. Plus, Daffy's had a few Batduck cartoons under his belt anyway.
- Road Runner as Flash is good. Or Speedy Gonzales if you wanted to be non-PC.
- Porky has to be Robin, seeing as how his best work was done as Daffy's sidekick.
- Wonder Woman? As much as I hate "Space Jam", I guess Lola Bunny's your best bet. She's the only memorable female Looney Toon ever.
- Hawkman - Foghorn Leghorn. Why the hell not?
- Tweety Bird takes the position of the Martian Manhunter. Look at the shapes of their heads. Both freakishly big. Both fairly round. That's the key.
- Green Lantern could be... uh... somebody... the first unused good guy Looney Tune I can recall. Maybe Pepe LePeu. Sure, whatever. I'm grasping at straws now.
The Bad Guys -
- Elmer fudd as Lex Luthor is the only logical choice.
- Sylvester - well, based on name only, I guess that makes Sylvester Sinestro. Sylvestro. I like it.
- Marvin as Braniac, still perfect.
- Taz... Joker? Nah.