Ultra-sun: Spacing out is basically all it does. It turns back into Slowpoke if its tail, along with Shellder, breaks off.Moon: Whenever Shellder bites down hard on its tail, it gives Slowbro a flash of inspiration...which it forgets a moment later.Alpha-sapphire: Slowbro’s tail has a Shellder firmly attached with a bite. As a result, the tail can’t be used for fishing anymore. This causes Slowbro to grudgingly swim and catch prey instead.
Prof. Lotus' Notes: The relationship that Slowpoke has with Shellder is parasitic. The Shellder on it's tail is constantly pumping poison into slowpoke to 'motivate' it to do what it likes.