Sue Richards
Mr Fantastic
Dr Doom
Dr Strange
Zero
Sue can create a forcefield of a caliber that can protect the other four whilst Zero ports them all away. Using his magic, Strange can mask their location whilst Doom and Reed create themselves some nice hardware. Once prepared they may return to the battlefield, where Doom shall move forward to engage Thanos. Having taken a blast from Thanos with the IG in his basic armor, I have no doubt he will be reinforced to the point where he can trade blows with Thanos for long enough for Reed to prepare his weapon. If Thanos decides to ignore Doom, he will have his powers removed much like SS has, or, barring that because of some protection, will be facing the wrath of whatever Doom has cooked up. Now, here's the best part, if at any point any of the combatants are in danger, Zero ports over, pulls em out, whilst Strange provides whatever nessecary support.
The idea is that Sue can provide cover for Reed to use whatever he can come up with (Nullifier anybody?), Doom can stand up to Thanos, Zero is our safety boy, and Strange can augment any of their roles with his magic.
If this team doesn't have a shot, I don't know many who do.