Shroodle is a tiny shrew-like Pokémon with an almost hemispherical body, having a stubby tail and four small white feet with gray paw pads. Its fur is gray on top and white on the underside, except for its black head, which takes up about half of its body. Shroodle's head contains large, yellow-green eyes with tiny black pupils; small semicircular ears on the sides; a single tuft of blonde hair on top; and a long, bulbous snout at the front. The snout contains a pair of sharp upper incisors, coated in a purple poison that can cause paralysis.
Shroodle has a mellow personality, but if angered, it will bite into the offender, inflicting them with its venom. It paints markings around its territory using a poisonous liquid with a sharp, unpleasant smell, in order to ward off intruders.
Shroodle may be based on the Iberian shrew or the Pyrenean desman, two species of shrew found in the Iberian peninsula. Its venomous bite may be inspired by the fact that certain shrew species are among the few venomous mammals, and have a venomous bite that is used to paralyze earthworms and other prey.
The shape of Shroodle's snout, combined with the fact that it evolves into a Pokémon based on an aye-aye, suggests that it also may be based on a treeshrew, a small mammal from Southeast Asia that is believed to be the closest evolutionary relative to primates. Its large eyes and evolutionary line could be inspired by mouse lemurs.
Shroodle may also be based on any species of shrew tenrec in the genus Microgale, which are native to Madagascar just like the aye-aye. Tenrecs in general have the unique behavior of licking their paws and spreading their saliva around their territory as a method of scent marking.
Shroodle's overall body shape may pay homage to "Kilroy was here," a popular graffiti.
Shroodle may be a combination of shrew (insectivore mammal), shrewd, and doodle.
Shirushrew may be a combination of 汁 shiru (juice), しるし shirushi (mark, sign), shrew, and シュルシュル shurushuru (onomatopoeia for rustling).