What happen when Dragon Tail and Counter in the same turn?

Question

I'm asking many question about Counter but I'm confused with this move and I want to understand how it works.

So the question as you read above, what would happen? Counter fail and Dragon Tail hits or Counter will make the last physical-move used or last physical-move reflected by Counter?

For who don't know, Counter has -5 priority and Dragon Tail has -6. So Counter will strike first I think?

Answer 1

Counter would go first under normal circumstances and fail because the opponent hasn't used a Physical Move against you (not before you at least, as Counter is -5 Priority, while Dragon Tail is -6 Priority). Dragon Tail would then hit and force the target to switch out, unless they have the Ability Suction Cups, is under the effects of Ingrain, or has a Substitute set up.

Source: Experience