A Spheal's fins are too short for anything except digging through snow; instead, they use them to steer when rolling around the many ice-filled caves they call home. Moving in this way is not easy, and stopping even harder; to cross from one end to another, a Spheal must solve many puzzles, stopping at some pillars of ice to change direction and angling their bounce off others. Indeed, young Spheal frequently wind up in the water on the lowest floors of caves, trying constantly to work their way back up only to fall again and again. Even older, stronger Spheal regard reaching the cave exit as a grand achievement, so they often bring back items from the outside as proof of their triumph.
The icy floors that Spheal call home are no easier to navigate for other pokemon, and humans venturing near carry escape ropes lest they be trapped there forever. To capture Spheal, trainers developed a custom of seeking out spots where their pokeballs would be returned to them by the incline of the ice, then rolling them at the Spheal. Because their other pokemon could do little more than fall, trainers began to whack the Spheal with these balls repeatedly to weaken their catch. When most shots missed, they used their feet to try again and again, often banking the balls off pillars of ice. They were as remarkable for their determination as their ingenuity; when the pokeball rolled back through their legs or off the ice sheet, they would start anew with their next one and keep going until either they captured the Spheal or (more commonly) they ran out of pokeballs.
It was the desire to spread this challenge to the rest of the world that led to the invention of pokemon pinball.