On the website, it says slowpoke evolves into slowbro when its on level 37. I thought it evolved when shellder clamps on its tail. Please help me. Thank you.
Since there is no way in the games to get Shellder to latch onto a Slowpoke tail (or head in the case of Slowking), level-up is how it is done.
In the anime though, Slowpoke will evolve when a Shellder latches onto its tail.