1. The Crime Syndicate
Last year I watched Justice League: Crisis on Two Earths and I loved it, I think it would be great material for a live action adaption with a couple of things changed of course. If I were Warner Brothers I would cast their second choices for that would've played each of the heroes. It’s a great story and it will teach the Justice League that there is a reason people fear them, it’s gold. Also, they're freaking evil and epic so why not?
2. Green Arrow
It doesn’t need to be Stephen Amell’s Green Arrow but with the TV show they’ve proven that Green Arrow is an awesome character and when done right can rival the bada**ery of Batman. I think he could be a vital part of the Justice League later on further connecting these "gods" to humanity and keeping them grounded.
Darkseid is one of the purest forms of evil; he is looking for the anti-life equation. The anti-life equation would grant him power over just about everybody's freedom of choice thus taking away their ability to "live". He owns a planet called Apokolips and he oversaw the training of Big Barda and The Female Furies. All of those women contest Wonder Woman’s fighting ability so his champions are no joke, especially when he takes Supergirl, which would make a very intense live-action feature. Darkseid is one of Superman’s ultimate enemies and he is one that never seems to go away, I am sure they will use him eventually if not in the next 5 years.
No, I do not want to see any version of Robin under the age of 16. It wouldn't work to have Batman with some child fighting mob bosses, psychopaths, and super-humans it’s child abuse. I would however like to see the matured versions of the Robin mantle including Jason Todd, Tim Drake, and Dick Grayson. We would most likely see Nightwing whom has been rumored to be in Batman vs. Superman but it seems to have lost it’s steam. I would love to see DC/WB’s take on Batman: Under The Red Hood.
Amazo is a great Justice League villain who knows how to bring it, he copies powers so he's near invincible. The league would really have to come up with a plan to take him down, not just punching him, which adds some depth to the team. In the JL/U series Amazo came around originally as a villain but then he had a redemption story and became a hero. There are some really fun, and compelling stories you can do with an android.