Groilla is a green monkey-like Pokémon that drags its clenched fists on the ground. It has a tail which resembles a leaf and has its eyes right open, always ready to attack. It also has what appears to be a leaf on its head. It has two dots as its nostrils and a dot as its mouth. It has an unsual red marking around its eye and has red stripes that lead up to its pale fists. It walks on its two back legs, which are smaller than its fists.
Females have smaller tails than males.
Groilla are very timid Pokémon. They would rather throw hard fruits at their enemies from trees than to face them on the ground.