Quick thing, right now DD Gyarados just absolutely wrecks you. Standard DD/Waterfall/Stone Edge/Earthquake or even Sub/DD/Watefall/Bounce sets kill you because you literally have no answer to it. It can DD on Scizor/Dragonite/Ambipom/Vaporeon easily, proceed to set-up and sweep. Simple solution (since you're using one of Gyara's best counters anyways) is to use HP Electric over Toxic on Vaporeon. Gyara can't KO it one hit (even at +1), but HP Electric will maim it.
Thank you for the advice, however I'm a little confused on how HP works. I know it's based on IVs but since theres no way to determine what IVs your pokemon has how would you end up getting it in the actual game? Lots of trial and error?
Having both Swampert and Vaporeon together is kinda redundant don't you think? Try out Blissey:
-Wish
-Protect/Softboiled
-Seismic Toss/Flamethrower
-Toxic/Thunder Wave
Nature: Bold
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers
Ability: Natural Cure
And with that, half your team is vulnerable to Fighting opponents. Try out Gengar:
-Substitute
-Pain Split/Hidden Power (Fire)/Thunderbolt
-Shadow Ball
-Focus Blast
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb/Black Sludge
Im not quite sure what you mean by redundant? Are meaning becuase theyre same type? My reasoning was that Swampert is immune to electric and his moveset would set him off from any other water types.