Nymble is a gray, oblong, insectoid Pokémon resembling a grasshopper, with dark gray colorations on its face, back, and legs. Its head has two stubby semicircular antennae, a circle on its snout resembling a mouth or nose, and yellow compound eyes shaped like rounded crosses, complete with cross-shaped black pupils. Its body is divided by lines into multiple segments, and it has an X-shaped pattern on its underside. It has six legs: two pairs of legs are located on the sides of its body, and each of the forelimbs are dark gray and contain a single claw. The third pair of legs is located above its body and is much larger; they are oblong in shape and solid dark gray in color, with light gray ring patterns over the joints. Nymble always keeps its third set of legs folded up.
When threatened, Nymble can jump to a height of over 30 feet (10 meters). Its jumping capabilities allow it to dodge attacks while dealing damage.
Nymble appears to be based on a grasshopper. The fact that it cannot fly, unlike most grasshoppers, may suggest it is based on a meadow grasshopper, or a grasshopper in its nymph stage, which is alluded to in its English name. It may also be based on pygmy mole crickets due to its coloration and rounded features. The way its third set of legs fold up resembles pocket knives.
Nymble may be a combination of nymph (immature form of an insect) and nimble.
Mamebatta may be a combination of 豆 mame (prefix for small) and 飛蝗 batta (locust; grasshopper).