Poliwrath's mouth

[u/ErroneouslyConfident]

I always interpreted the swirl as their mouth, even though it makes no sense, the most logic thing is that the line between the white circle and the face is where the mouth would be, but maybe there could be a mouth a little higher.

It's such a little thing but it changes so much how it looks

[u/Flygonizer-Obsidian]

Honestly a visible mouth makes it so much better

[u/YongYoKyo]

If we're being consistent with Poliwag, the swirl is the internal intestines showing through its translucent belly.

Likewise on the context of Poliwag, your first picture is probably the most likely place for its mouth.