the 100 % sure way to catch it is simply to use a master ball
wooper is in Ruin vally on Island Six
Well, In the Great Marsh. Roselia
I'm not sure if it's possible to catch Wooper with a good rod, but you can find it in the tall grass in the Great Marsh, which is located in Pastoria City.
in route 212 in pastoria city
Try looking around route 32
Route 212 (Diamond/Pearl only)
You have to look around in the Marsh Area in Pastoria City. They are very common there.
i think you have to evolve wooper go check on seribii.com rbygsc pokedex
first you need to beat the Pokemon league in ever grand city when you do go to the safari zone if you see a new path go to the waterfall the surf around on water then you will meet a wooper
cliff cave, cliff edge gate , ruins of alph and union cave . [[ use surf]]
you can catch one for yourself in the safari area in the city with gym leader crasher wake.
Yes, Wooper does evolve. Wooper evolves into Quagsire at level 20.