Ok, here is my Leavanny.

The Bug the that was on Broadway:

Nature:
Jolly.

Ev's:
252Atk/Spd 4Def

Item:
Choice Scarf/Focus Sash

Ability
Swarm

Moveset:

Entertainment
Me First/Leaf Blade/Payback/Ariel Ace/Shadow Claw
X-Scissors
Sword Dance/Leaf Blade/Payback/Ariel Ace/ Shadow Claw


Alright, I decided to use a Leavanny with Entertainment because it was something new and unique. Basically, when a Pokemon that you're sure is holding no "Bug" moves switched in, you hit them with Entertainment and either force them to switch, or force them to fight with a useless ability. Me First is an option for when slower Pokemon switch in, and you think you can accurately predict their next move. X-Scissors is Leavanny's best STAB attack, IMO. Sword Dance is kinda risky to run, due to Leavanny's frailness, so instead of running Sword Dance (or Me First) you can choose from a list of other attacking moves. Leaf Blade is a great STAB, and can destroy Bulky Water/Ground Pokemon. Payback has weak BP, but can hit Psychics/Ghost for a lot of damage. Ariel Ace can do chunks of damage to Volcarona, or any other Bug/Grass Pokemon. Shadow Claw can take-out Ghost/Psychics with ease.