If Slowking is UU, then yes, I use Slowking.
Slowking is always cited as the lesser of the Slows because as a special wall he's weak to T-bolt, G-knot and S-ball. But really, any unboosted non-stab one of those moves isn't doing more than 35% on him, and he can just Slack Off the damage after he Trick Rooms. He can easily go head to head with T-bolting Starmie, Nasty Plot to max and KO with Surf without ever going in the red, ready to sweep with two or three turns of Trick Room behind him. (I've done this many times.)
I have a Slowbro on my team too, though. The identical typing looks like it'd be a crippling disability, but it isn't.