Seeming as how we already have a good steel STAB in Meteor Mash, I want a good physical ghost STAB with a helpful scout-ish second ability.
So from there I come up with...
Shade Wave
Type: Ghost
Power: 95
Accuracy: 100%
Class: Physical
PP: 5
Priority: 0
Secondary Effect: All of your oppenet's pokemon who enter battle have a random (uniform) proabality of having their held item, 2 moves or abilitiy revealed. This effect will stay present on the field for 3 turns or until the move rapid spin is used. This secondary effect has a 75% chance of activating, assuming that Shade Wave hits a pokemon for damage.
And now for reasoning. As I said, I wanted reliable Ghost STAB with decent power and scout-ish effect. The power could have not have been too high for fear of brokenness, but not too weak to use shadow claw instead. The PP, however, must be low so this effect can be effectivly stalled out.