Flash Cannon or Sludge Bomb for Clawitzer?

Question

I have a Clawitzer and I can't think which move should I gave it. Here some info.

Aura Sphere
Dragon Pulse
Dark Pulse
???

Nature: Modest
Ability:Mega Launcher
Item: Life Orb

The reason I want it to learn Sludge Bomb or Flash Cannon, so if I ever battle a fairy Pokemon I got this moves to deal some damage, since Fairy's hate poison and steel, but I can't think which move is better.

Answer 1

I would actually say that you are gaining triply more with Sludge Bomb than Flash cannon.

1. It attacks Fairies, like you say, but also Grass types are harmed by its 90 BP, which actually is higher than Flash Cannon's 80.
2. It can poison. Nuff' said.

So yeah. Sludge Bomb > Flash Cannon.

Answer 2

What I would run on Clawitzer
Clawitzer@life orb
Nature: Modest
Trait: Mega launcher
Evs: 252 sp attack / 252 hp/4 sp defense
-Water pulse (STAB)
-Sludge bomb
-Dragon pulse or Flash cannon
-Aura sphere

The reason I'd run this is because dark is only super effective against ghost and psychic not really good coverage there. Sludge bomb covers super effective grass types. Water pulse is for STAB. Aura sphere covers fighting, steel, ice and normal types. Dragon pulse is just for dragons.

This is my personal preference but use what you feel your team needs coverage in.

Hope I helped :)