The only place you can actually find Politoed as a wild pokemon is in the pond of pal park.

The other ways to find Politoed is to evolve it from Poliwhirl, by giving Poliwhirl the king’s rock and trading it to another game.

But you can always catch a Poliwag and evolve it to a Poliwhirl, and then, evolve it into a Politoed.

If you want to catch poliwag, go to this website to find out where it is located:émon)#Game_locations