I have thought about this for quite a while and after crossing out plenty of names, I finally narrowed down my list of villains to four who could be part of the greatest Suicide Squad of all time. I chose these characters not because of popularity, but because I know they could be the ones that not only get the job done and kill the targets, but also kill their spirits along the way.
So let's start with the leader of the group....
1. General Grievous
With previous work as a general, Grievous has plenty of leadership experience, especially when it comes to battle. He is a dedicated fighter with plenty of skill. He takes pride in the deaths he causes and will keep the lightsabers of fallen Jedi as trophies. This pride, dedication, experience and ambition is a necessary part of the new Suicide Squad that will lead them to success. It should be noted that General Grievous does have one very vulnerable weakness: being shot in the chest. But that's a weakness to almost everyone. The fact that it is his only weakness is amazing. In any case, as the leader of the team, Grievous will commonly sit behind-the-scenes for much of the action, only to reveal himself once the target is cornered to strike that last bit of fear into the target's mind that this robotic creature with four lightsabers being wielded in his four arms will deal that final blow into oblivion.
Mystique may not always be the most inventive character when it comes to battle strategies, but she certainly can get a job done in her own unique way. Her ability to change form is remarkable and she is also very dedicated to her work, often taking large amounts of time to work on a separate cover identity just so she can kill her target. Mystique's ability to not only change her form but also take in an entirely new persona will be a very useful tool to the new Suicide Squad as she will be able to infiltrate the target or targets' personal lives without being noticed, only to strike at precisely the right moment. And once people begin to realize Mystique is out there trying to infiltrate them, she will be even more useful. The targets will be so unwilling to trust anyone out of fear that they will soon become isolated and turn on each other.
Yes, another Marvel villain. But it's all for a reason. Carnage will serve as the brawn of the team. Grievous may be the planner and Mystique may be the deceiver, but Carnage just wants to be the killer. He is one of Marvel's most feared and most powerful villains. The combination of the Venom symbiote with his rage, hatred and murderous attitude enhances his abilities beyond compare to make anything in his way a total bloodbath under his unstoppable power. Now Carnage may not be as strong as any of the variations of the Hulk or other characters like that, but Carnage has something better than them instead: a willpower. Hulk, Red Hulk, Gray Hulk, Abomination, etc. all have one weakness in common: they can't control themselves from destroying stuff. Carnage, on the other hand, can control himself. He just chooses not to. This rage and immense amount of power will be enough to help the new Suicide Squad take practically anyone down, especially after the rest of the team does their job.
4. Freddy Krueger
Probably the most obscure team member yet, Freddy serves as the key to this Squad. When the rest of the Squad fight and strike fear into the targets in reality, Freddy fights and strikes even more fear in the one place no one else can reach: their dreams. No matter who the new Suicide Squad is hunting, there's a very large chance that the targets will need to sleep at some point. But will they be able to sleep once they dream of Freddy hunting them down and wake up to find their friend dead with slash marks across their chest? No, they won't. They will begin to fear sleep, knowing that they will be even more vulnerable there than in reality. They will quit sleeping, and they will never be able to recover from that unless they go back to sleep. If they sleep, they die. If they don't sleep, they won't have the strength to protect themselves from the rest of the Suicide Squad in reality.
So That's the New Suicide Squad
Though almost none of these villains have ever had contact, together they create an unstoppable force that can put an end to any one, be it an individual or a team. General Grievous will tear down their strategy. Mystique will demolish their trust in others. Carnage will conquer their strength. And Freddy will vanquish their sanity. Fear will be their greatest weapon, with Carnage attacking during the day, Freddy attacking during the night and no knowledge of when or where Mystique is attacking. And when Grievous finally reveals himself to the target, when all hope is finally gone, the target will wish he had just died in his sleep instead of running from his inevitable doom at the hands of the Suicide Squad.