Thunder Wave Slowbro is good, yes. He kinda suffer from four moveslot syndrome though. You run Slack Off and any three of Scald, Psychic, Fire Blast, Thunder Wave and Yawn.
Yawn is really a secondary option, but Slack Off and Scald are mandatory. Psychic, Fire Blast and Thunder Wave check different things, depending on what you need. This is what makes Slowbro great, really. It doesn't just sit there and take hits, it threatens stuff. Base 100 Special Attack is decent, useful double STAB is useful, and stuff like Disable, Trick and Calm Mind can give the opponent an unexpected headache. Throw Calm Mind on your Slowbro, and you have a physical wall + mini Reuniclus!
Psychic is used for Conkeldurr, who you don't want to Scald, and Toxicroak.