So, this question started with a story...
A long time ago, I was playing Pokemon Diamond and I came across a Skuntank. I attacked it and it didn't faint, but then it used Memento and died.
So I basically thought "how the heck could that move be useful?"
Just look at one of Pimpnite's epic sweeps
Hope I helped!
Its a really bad move, but I can think of two reasons it might be used.
Basically, it's still a really bad move and not worth wasting a moveslot for.