User blog comment:LegerPrime/Natsu vs. Acnologia/@comment-25962249-20151013041545/@comment-25962249-20151015064038

It doesn't really matter. Acnologia in human form is stronger than just about everyone, when he goes in dragon form, he is akin to a god. It doesn't matter if Natsu is in dragon force, or even in END mode, he will be crushed in his current state. Even with his training, all the Dragon Slayers together would not be able to take him down. Give it 5 years or so and they stand a chance, or 10 if he is to solo fight him.