Gyarados 1v1 Piloswine, any tips?

Just use Machamp...or Entei or Venasaur. They all have powerful two bar moves...dodging is basically never a good idea.

Power up your gyarados

Why use gyarados? Use machamp!! I beat piloswine with atleast 30 seconds remaining. I can solo piloswine with my level 35 torkoals!! Its too easy!

You are trying to beat Piloswine with nothing but 1 Gyarados? A team of Gyarados? I'm confused

According to Pokebattler, with a level 35 Gyarados, it is very challenging to 1v1 it. You found the only moveset where it appears possible, and you have to dodge all the bulldozes. The white flash and the late dodge window for bulldoze should make it a bit easier, but still difficult until you level up some more.

Actually, Kyogre gives you a higher 1v1 winning chance against Bulldoze Piloswine...

But you need not dodge PS or IS. Just dodge Bulldoze, every single one of them. And launch your Hydro Pump after a Bulldoze. Hydro Pump is not very slow like Solar Beam so you won't miss dodging the next Bulldoze.

Waterfall is a high DPS low EPS move, which means that you should probably keep doing it until a Bulldoze happens and you can launch HP after dodging.
I don't have experience on the matchup but it could also be possible that if you launch HP right after seeing a fast move, you'd recover in time to dodge a BD that comes next. Lugia's SA works like that against C/CC Machamp, but you'll have to either do the math or experiment to see if it works.