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 the Pastoria City Great Marsh, and on Route 212. The catch rate is 225, so that's good.
yes
You can catch it almost anywhere, but you need the good rod to catch it.
Wooper is water and ground type, so a grass type should do it.
Action Replay is a very good friend.
You can catch Beautifly in Pokemon Platinum in Eterna Forest at Level 14. However, there's only a 1% chance of spotting one, so good luck.
The route right before sunnyshore city you have to catch it with a super or good rod
at stark mountain
Madgikarp, Sheller, & more basic water Pokemon! :)
route 222 (good rod) mainly magikarps
a good rod or super rod
you migrate a lv 100 Pokemon from GBA, then catch it in pal park hope this helps (buy used gba they probably have good Pokemon)