Maybe, but I use it to destroy more powerful mons that will give Moltres trouble in the long run. If they try to kill me, I get my revenge and thats one less mon Moltres has to worry about. Also, I use DB with a bulky set to make it more effective.
Okay, that makes sense. ^^
I haven't had problems with either of them. I just bring in Spiritomb while their boosting and kill with Foul Play. That's why I use defensive Spiritomb because it can live a boosted Waterfall from Feraligatr.