Griffon is a great trapper against the wraith, especially when paired with Bucket’s UAV. His harpoon easily nullifies the wraith’s decoy (I have done this many times). His spikes are useful, but they can be avoided by a cautious monster (hard to be cautious with Bucket’s UAV continuously hounding you). His SMG is far superior to Maggie’s due to the large clip size and no recoil.
I would not, however, call Griffon the hard counter to the wraith. He has nothing to stop the wraith from punishing him while in the dome. Abe and Maggie have delaying maneuvers that allow a chance to evade the wraith around tight corners. Abe is able to slow the wraith’s movement continuously, and there are other classes who have ways to combat decoy (although not as effective). Caira and Hyde can burn him to reveal where he is for a while. Abe, Cabot, and Bucket can tag him so as to locate him easily after the decoy is gone. I have not seen Val’s tranq against the decoy yet, so I don’t know if that would work (tranq after decoying reveals original?). Also, without tracking support from another class, a completely stealthy (and perhaps lucky) monster can evade you for while.
In short, I would call Griffon the hard counter to the decoy but not the wraith.
One final note, I have also had great success with a Griffon/Hank combo against the wraith. Not easy to track, but Griffon can harpoon stop the decoy while Hank can airstrike the nova dome and shield targets effectively neutralizing the two most valuable abilities with the wraith. The addition of Caira makes this team even scarier.