Could the Daleks defeat the Avengers?
The Daleks would curbstomp the Avengers, and they wouldn't need a single infinity stone to do it. The Daleks have brought whole galaxies to their knees by their own power.
They operate on a scale that, without the Infinity Gauntlet, Thanos would never be able to match.
Unless Iron Man could get aboard the command ship and MacGuyver a solution together, there is no chance for Earth, or the Earth's Mightiest Heroes, to survive this fight.
The Daleks curbstomp the Avengers. They're equipped with planet busting tech on their ships, which they consider to be antiquated, galaxy busting tech is the meta for the Dalek Empire and if that isn't bad enough they also has universe busting and infinite multiverse busting tech as well. Out of all of the Avengers, only Thor or Hulk might have some chance against the Daleks but then again, the Daleks might be more interested in using them in their experiments.