Alongside its water-typing, Slowbro has psychic powers making it a water-psychic pokemon. Unlike it's counterpart, Slowking, Slowbro cannot talk but is more physically bulky. After getting bit by a Shellder, Slowpoke becomes Slowbro and it goes through an evolutionary process, where the two organisms for a symbiotic, almost parisitic relationship. The weight has forced Slowbro to become bipedal and instead of fishing for food it has to physically catch it, this allows it to have its arms free making Slowbro able to perform moves such as Brick-Break.
If ever a person should have a wild encounter with a Slowbro, the appropriate course of action would be to state "Yo bro, it's a Slowbro!" followed by a repeated assault until it submits to your pokeballs.