The first set of Spuds MacKenzie commercials, which you can view above, followed a pretty strict formula: a party is going on, a dog named Spuds MacKenzie arrives with some Bud Lights, and people lose their shit. That's literally it. There's a Beach Boys-lite theme song in one version that dubs him "a super party animal," and the jingle gets a reggae and country remix in the other spots. Sometimes Spuds wears sunglasses. Sometimes he rides a skateboard. In one ad, he plays the drums.
Like many things from the '80s, Spuds MacKenzie is so defiantly low-concept that he can be a little difficult to explain. As noted in this excellent Mental Floss history of Spuds, the ads were designed to be slick parodies that used "overt self-awareness" to cater to the audience's hip sensibility. The simplicity of the ads -- or the dumbness, depending on how you view it -- flattered viewers who thought they could see through cheesy commercials.
Does the dog have a catchphrase? No. Does he talk? No. Do bikini-clad women in the commercials imply they want to have sex with him? Yes. If you compare the "classic" '80s version of the ad to the new one, that creepy, leering quality has been replaced with a more modern message about the canine beer enthusiast wanting you to spend time with your male and female friends. Apparently in his ghostly form, Spuds is less of a lothario.