I've got this so far:
Crobat @ King's Rock
Trait: Inner Focus
EVs: 252 Attack / 252 Speed / 4 HP
Adamant nature (+Attack, -Sp. Attack)
What should move number 4 be? This is in HeartGold.
Even though these suggestions are good, there are some better choices. Like Roost so you can heal your BB damage, X-Scissor to cover your Psychic weakness, Confuse Ray for Confusion Hax, Zen Heatbutt for regular coverage, and so many more choices! I know you have U-Turn for Psychics but that's okay, as it is mostly used for scouting. But since you can use X-Scissor without scouting, that is a good choice. The move I recommend most is Roost, since you don't have lefties to heal your BB damage. But if you decide to put lefties on Crobat instead of the Kings Rock, then use Confuse Ray to confuse your opponents then use U-Turn to escape. The choice is yours, I just made recommendations :P. Hopefully this answers your question.
Hope I helped!(ish)
Which gets STAB,it has a chance of poisoning the foe and has high chance of critical hit.
Edit: If you are all about coverage,go for bite.
Bite covers phychic type plus chance of flinching.
I would choose cross poison for poison STAB and poisoning chance.