-Grimer is found in Fiery Path
-Corsola is found in the water using Super Rod near Ever Grande City
-Vulpix is found in the grass on Mt. Pyre
-Pichu is made when Picachu is breed with another Pokemon of that egg type or Ditto
-Vileplume is evolved from Gloom using a Leaf Stone
and Jigglypuff is found as so...
-go to the beach north of Rustboro City
-Surf as far north as possible
-you should see a tiny beach (with no trainers on it)
-go on the beach and go north
-you should see trainers - either go past them or battle them
-you should find a patch of grass, there you'll find (rare) Jigglypuffs and there are high level Taillows and even Swellows