Bulbapedia is leaning toward chespin as a hedgehog.
"Chespin is a combination of chestnut and pin. It may also be from urchin (an old term for hedgehog), chinkapin (the name of some species of chestnuts), and spina (Latin for thorn).
Harimaron is a combination of 蝟 harinezumi (hedgehog), 針 hari (needle), and marron (French for chestnut)."
Pin makes sense for hedgehog. A chestnut and a pin cushion. Chespin.