Yeah, it seems like you gotta dig deep and you'll see the niches. Being a threat to Wash Rotom is definitely worth something because not only will it resist its attacks but it can also hit it back with a Grass move. The 4x weakness to Ice is the biggest downside though.
And there won't be many options to be able to paralyze it, the only things I recall able to paralyze it will be Tri Attack, Freeze Shock (which have secondary paralysis effect) and also Thunder Wave if used by a Pokemon with the Normalize ability.