You fish in the new bark town lake
Shiny Poliwag can be anywhere in water, but you would have a very very very little chance of finding it.
I know where you can find a shiny Poliwag! Surf the water north of Violet City.
Poliwag can be caught by using any kind of rod in Route 43 (Pokémon Heart Gold / Soul Silver)
To find a Poliwag in Soul Silver, just use your old rod in the water in the Ruins of Alph. The first time I put my rod in the water, I caught one! :)
HootHoot, Stantler, Gastly, Drowzee and Poliwag
Poliwag can be found in many locations in Soul Silver. For example: Routes 6, 22, 28, 30, 31, 35, 43, 44 and 45. Higher level Poliwags can be found at Mt. Silver and by fishing in Cerulean Cave.
Sorry to burst your bubble, but it doesn't evolve, because it's the last evolve form of poliwag.
Poliwag evolves into Pilowhirl which then evolves into Poliwrath
Poliwag > lvl 25 > Poliwhirl > (water stone > Poliwrath) (trading with King's Rock > Politoad)
you can not get regirock in soul silver but in platinum you can in a special event.
You can find Water-Type Pokemon with fishing rods. Old rod usually pulls out Magikarp, Krabby, and Poliwag with terrible moves. Good rods pull out better Poliwag, better Magikarp, maybe a kingler, and after you travel to Olivine, an occasional Corsola. Super Rod pulls up Gyarados, REALLY high leveled Magikarp, Corsola, Poliwag, Whiscash ( In swarms at Voilet...), and others... You can also find Marill in swarms at Mt. Mortar.
there isn't