For a team to be effective, it needs to have certain principals in place. Certain types of different Strengths to combat different types of problems. Here's my list of the most unstoppable team you could assemble to do your bidding.
1. Lex Luthor
Lex Luthor is considered to be the smartest (human) man in the DC Universe. He has a high enough intellect to go up against the likes of Superman. Time and time again. This man knows how to beat you at chess in 100 different ways before the game even starts. Let alone his intelligence when it comes to science. His Brain alone makes him a HUGE asset to this team. When you require a Genius to solve a high intellect problem, Luthor is the guy you want.
2. Darth Vader
This being of the Dark Side is capable of a endless number of abilities. Things like telekinesis, lightsaber combat, force choke, force repulse, force crush, force rage, force lightning, saber throw, levitation, mind tricks, breath control, force heal, force speed and force sense. So not only is this guy nearly incapable of being beat alone, he also has the powers of telepathy and precognition. So he can also use the force to see the future and what you have planned!!! He also can communicate to his teammates from great distances away without the need for tech. This guy alone is a Suicide Squad. Only it would be your suicide if you decided to take him on. Darth Vader can not only handle the psychical aspects of combat, but can also use his power to retrieve information from peoples minds without them even knowing it.
Darkseid is so powerful that only the likes of Superman, Doomsday and Orion really mean any threat to him at all. He has powers matching Superman's, but also a few bonus ones as well. He has great enough speed to react in nanoseconds along with his ability to increase his size and teleport himself to various planets and throughout the course of history. He also has a back round as a warrior and would be more than capable at drawing up a battle plan. Not to mention his most infamous power, his Omega Beams. These beams are nearly impossible to evade. They can turn corners, go straight, do a 360...wherever Darkseid wants them to go they will. They also grant Darkseid the ability to RESURRECT the dead. So IF one of his teammates were to be vanquished, he could resurrect them at will. When your team does not stay dead, that is the definition of Unstoppable.
Doomsday is the being that killed Superman. That just about sums him up. He's literal invulnerable to anything a human can dish out. Though one problem he does present when working with others. He hates all forms of life and would probably make an attempt to kill them as well. The answer to this would be to have either Vader and or Darkseid use their telekinesis powers to control Doomsday to do their bidding.
In conclusion, the beings making up this team are a Genius Scientist, a Sith Lord and two of the most powerful Kryptonians available: Darkseid and Doomsday.
If you, Movie Pilot, truly believe that this combination can be beaten, then challenge this team with a follow up explaining how they would be defeated BEFORE they accomplish their plan. Because remember...this is a Suicide Mission!!!