One Pokemon that I used to defeat the Elite 4 and Champion

My one pokemon that I use to beat the elite four is my Empoleon level 90.

Moveset-Surf, Waterfall, Drillpeck, Cut

I used a pp max on surf, and pp ups on waterfall. Use Drillpeck on Aaron, use Waterfall and Surf on Bertha and Flint, and anything on Lucian. Just use Surf on Cynthia's pokemon, except for Roselea, whice you use Drillpeck on. Hope I could help!