Seeing as you can beat the Champion with just a Magikarp and a squad of Gastly, Anorith definitely works. Its Attack is solid for in-game, and it gets some pretty good moves. Eviolite helps to patch up its defenses, and it'll be outspeeding a lot, because this is in-game. It has STAB super effective against Milo, Kabu, Melony, Piers, and a few Pokemon in the Champion Cup, meaning it can absolutely pull its weight.
Anorith @ Eviolite
Ability: Battle Armor / Swift Swim
- X-Scissor
- Rock Slide
- Brick Break
- Body Slam
Hope I helped!