Look, if you're going to be a scrub and ignore the facts when I'm trying to help you, be like that. Putting damage on the bench will NOT stop any half way decent Gyarados from setting up. Being an optimist is stupid when it's a proven fact that your strategy won't work. It's like getting in a car that's almost out of gas and going on a 100 mile trip and just hoping that you'll make it on the little fuel you have.
I suggest you try to find a different strategy for beating Gyarados. I'll be willing to help you, but you need to be willing to listen first.
Then why are you playing SP?
Perhaps you're forgetting that to have a gyarados you must first bench a magikarp. If it's dead, you can't evolve it, can you?
Skarmory will not work. A donphan tech will knock it out easily. Saybleye can overconfident it after a few crobat drops. You run plenty of BTS to get rid of mismia. The only thing that can help luxchomp beat Gyarados is expert belt even though you will pay for that if they run a donphan tech.
You don't one shot the luxray X with Expert belt attached, but a donphan tech can with one bat drop. Once the first belt is gone the second can be easily taken care of.
your 'PERFECT' counter doesn't have anything on Combee; they can still pull a magikarp up with 30HP remaining with a honey item combee
also, in Gdos, I favor that miserable bad Mankey over Donphan; Donphan is too much of a hassle and Mankey is just one card instead of two. He's easier to retreat also, but it should be noted I haven't even tested Donphan.