He looks generally okay, but I have a " You don't have to do this, but it works great " suggestion here.
Replace his Leftovers with a Choice band, then take out Waterfall for Aqua Jet.
Priority + Ridiculously boosted up attack, makes for a hard hitting pokemon.
I like Muscle band here, although you might want to consider a Focus Sash, and Swarm.
Swords dance will benefit you more than Poison Jab.
You're going to have some serious speed issues, dump 196 or 192 of your defense EVs into Speed, even with Quiver Dance boosted, you'll need it.
Modest? Use Choice Scarf and Draco Meteor instead of Dragon Pulse.
Perhaps a Timid nature would suit you better, you're going to get ridiculous boosts on your Special attack anyway, also consider a Miracle Seed instead of Focus Sash.
Psyshock > Psychic.