If anyone here wants a limited series DC Comic where they actually DO exactly what Yahtzee is suggesting, get the 'Secret Six: Villains United' series. It starts off being set in the lead-up to Infinite Crisis, where you've got all the camp crappy 70s Batman villains (you know, the ones where all they have is some absurd gimmick, like Umbrella Man who goes around robbing banks with...um...Umbrellas, etc) who don't want to join the bad guys in their 'destroy the world' plan because they're too old for this crap / on parole and don't want to get jailed for missing their curfew checkin / sane enough to realise that they'll get annihilated in a fight between all the villains with actual superpowers vs all the heros with actual superpowers, and so they (a few get killed early, but the 6 end up being Catman - yes, the ultimate 'camp 70s batman villain - Deadshot, Chesire, Ragdoll #2, Scandal, the Fiddler and a random Parademon that's gone AWOL and doesn't know what to do now it doesn't have any orders).
Then they find out that Luthor's collection of supervillains have a policy of killing crappy 70s non-powered villains who turn down their 'invitation' to join, and start shitting themselves until they get a mysterious call from someone called 'Mockingbird' who promises he can keep them safe so long as they do some 'work' for him...
In the process they find out that they're being tracked down by the freaken superheros as well. Not just that, but this bunch of non-powered chumps find out that the 2 characters most intent on tracking them down are none other than the freaken BATMAN on one side and Deathstroke on the other (a major problem as they don't have anyone that can hurt him enough to stop him from just regenerating in a few seconds).
It's an awesome underdog series, with 'victories' like Catman finally getting his dignity back by training until he can fight Batman to a draw while the rest of the team break their captured teammates out of jail. Perhaps not quite an all-out 'villain' series, as the characters range from ones like Catman who acts semi-heroically and respects the non-powered heros like Batman and Green Arrow, but views the superheros as the equivalent of alien invaders imposing whatever 'justice' they feel like upon a helpless population (citing the Dr Light lobotomy as indicative of why he hates them), through to Deadshot who sets the team's rule of 'doesn't matter whether the job is for good or evil - as long as we get paid'.
Again, great idea for a film, particularly because they're limited edition stories so you can kill characters off and build proper character arcs without getting stuck with the 'endless sequels' problem. Would never get made though.