Well, Gyarados is almost ridiculously weak against Electric 'cause even if he looks like a dragon, he's actually Water and Flying. I've used my Luxray against every Gyarados I've faced and never had a problem. Um... let's see, I used my Gyarados against her Kingdra, since they're only weak to other Dragons and at the time, he was the only higher-leveled guy with Dragon-type moves I had. And then--

[Not admitting her massive fuck-up of using a Ground type against a Flying type for Donphan versus Dragonite,]

And then it was my Skarmory against her Dragonite. If you've got Dragon or Ice, definitely use those. Ice is super-effective, but Bing wasn't high enough level when I challenged her. Um -- my Vanilluxe, I mean.