I agree with Bob in this, at least at the beginning, WB can't make a good JLA movie by copying the avengers, but I don't think that jumping straight into a JLA movie would work any better. My theory is that you either do a Teen Titans movie as the team up, with the same kind of lead up as The Avengers, but different, or 2 man team ups, like Batman and Superman, or Flash and Aquaman. That way you don't need as big of threats, and you can have easy interaction, while still having the other heroes cameo. Now, the Teen Titans would need to be done very specifically to work, but here's my idea. Please note, this idea is based on the team from the cartoon, because that's all I'm familiar with:
Firstly, you need a new Batman franchise, with a Robin, I don't care which, just a Robin, And have the duo face off against one of Batmans stranger enemies, like Killer Croc, or Clayface.
Secondly, you need to have a solo Robin movie, this would probably work better if the Robin in question was Dick Grayson, so it could be Nightwing, but again, just a solo Robin movie, where they mention the Brotherhood of Evil and the Doom Patrol and have a supporting character named Victor Stone. Stinger at the end has a crashed alien pod.
The stinger leads into a Starfire movie, done in the same vein as Thor, but where Blackfire takes over Tamaran in the end rather than losing, so Starfire is banished to earth. Victor from the Robin movie should be injured enough for Bruce to cyberneticly enhance him, probably during the middle action scene, if there is one. Victors new look would be revealed in a stinger, again.
Now, we skip over a Cyborg movie completely, and have a Doom Patrol movie, with Beast Boy leaving the team at the end because he thinks he's being looked down on for being a kid. Stinger has BB walking through a nearly destroyed city, when he walks up to a hooded figure. He asks her what happened, and she just tells him to go away.
Next is a Raven movie, showing her trying to help people, but not doing well at it, because her emotions keep getting out of control. When she is overpowered at the end of the movie, she unleashes all her power, decimating the city, and having the stinger from the Doom Patrol movie play again, but from Ravens Perspective. Stinger has Cyborg up and about, his arm transforming into a sonic cannon as the last shot.
Finally, we get to a Teen Titans movie, where the 5 meet up in Jump City for some reason, TBD. Probably that Raven is still accidentally wreaking havoc, so the 3 independently go there to prove themselves, and Starfire is already there. Blackfire comes in with an army at the last act, so they have to team up to beat her back.
Your opinions?