Vaporeon vs Gyarados

Offhand, I know that the lack of stab on the gyarados quick move hurts it. Also, gamepress tends to value total damage, so tankiness is more important in rankings than it may be in real life, depending on how you play.

Outside of Golem or Rhydon, what exactly are people using Vaporeon for? I never use my water pokemon for attacking, just a Venusaur and Tangela.

https://pokemongo.gamepress.gg/q-a/gym-attackers-tier-list

This thread has an explanation from "dondon151", the creator of the list, that addresses that question exactly.

Basically he points out, Gyarados is not all that, even though many people seem to think it is.
For specialist tasks he is beaten by better specialist, and as a generalist he is nothing special compared to other stronger generalists.
He is a 'jack of all trades but master of none'

With all that said, you can still use him when and how you want - the lists release did not change that.

Because Vape is awesome~

I rarely ever use Vaporeon for attacking gyms anymore. But I do use vapes a lot for prestiging. I understand the thought behind Gyarados drop to tier 3+ but I think it was a little too extreme to make a point.