As part of its ongoing efforts to promote every single Pokémon out there, The Pokémon Company has shared special content dedicated to Poliwrath:
Did you know? It’s quite a gifted swimmer, even among Water-type Pokémon, but it normally spends its time on land. The muscles it has developed through swimming are thick and powerful. When it lands a square punch, it can turn huge boulders to dust.
Source: The Pokémon Company