#027: Sandshrew
Ungainly and slow-moving, Sandshrew rely on their rocky scales for protection when venturing above ground. Too heavy to be carried off by common predators like Fearow, and able to fend off many dangers when curled up in a ball, their greatest threat comes from unfavourable type match-ups. To avoid an untimely demise at the wrong end of a Razor Leaf or Water Gun attack, Sandshrew dig their burrows in hot, arid areas where the majority of grass and water pokemon cannot survive. Highly cautious creatures, they tend to stick to their tunnels if not looking for food or sunbathing, which makes them quite difficult for trainers to catch.
Only the brave, the foolish or the hungry would continue to pursue a Sandshrew once it makes it underground, as Sandshrew burrows are built like mazes. The pokemon live in large groups and dig extensive, looping tunnel networks, keeping their vulnerable young (newborn Sandshrew are soft and crumbly) safely in the centre. They constantly excavate new routes and alter old ones, yet never seem to take a wrong turn. For intruders, however, getting lost is the best possible outcome.
Each Sandshrew burrow has a few major tunnels marked as off-limits. (It's unknown whether this is done with scent or via some other means.) The largest members of the colony patrol these tunnels, not by their customary crawling on all fours, but by rolling at high speeds. In the confined space, with nowhere to run, the Sandshrews' greatest defence becomes an unexpected and deadly weapon. A rumbling is the only warning, before a boulder-like pokemon arrives, travelling at skull-splitting velocities.