Gallade @ Galladite  
Ability: Guard Up
EVs: 252 Atk / 4 Def / 252 Spe  
Jolly Nature  
- Swords Dance  
- Psycho Cut  
- Close Combat  
- Night Slash / Shadow Sneak

Mega Ability: Knight's Blade - Boosts the power of cutting, sword, and slashing moves by 1.5x (Psycho, Night Slash, Leaf Blade, and more)
Other Options: Leaf Blade, Sub + Bulk Up, Ice Punch, Thunder Punch, Poison Jab, Knock Off