migrate it!
Surf on Route 228 and you have a 50% chance of finding a poliwhirl and a 50% chance of finding a poliwag.
In the water
you have to trade a poliwhirl with a kings rock
routes 225 227 228
If you have access to Two Island, look in the Cape Brink for Poliwhirl.
you can catch a poliwag and evolve it into poliwhirl, and then use a water stone to evolve the poliwhirl into a poliwrath
you use a water stone
NO you cant catch syther in Pokemon pearl
You can't catch a charizard in pokemon pearl.
Diamond & Pearl: You can catch a Poliwhirl with a super rod on route 225. or route 225 surfing. or route 227. <(Surfing). and route 228 while surfing.
neither of them is better, they are both the same, but in diamond, you catch dialga, and in pearl, you catch palkia, and you can catch different Pokemon in each game for example: you can catch this Pokemon in diamond, but not pearl but: you can catch this different Pokemon in pearl, but not diamond
Poliwhirl can't be caught in Pokemon Ruby. You need to trade it from Leaf Green or Fire Red.