You go north from cherrygrove city.
West of Violet city.
you have to beat the elder at violet city
on the far left in the city
if its on pokemon soul silver, just use your super rod in violet city.
It is given to Mr. Pokémon near Violet City for experience.
Blue shard
On the path too the left of Violet city, someone will give it to you.
Just beat all the gyms. The first one is in Violet City
You can find quagsires in mt.silver cave. And woopers in the route under violet city
you will actually get the egg from elms assistant at the Pokemon center in violet city after you beat the gym leader there.
I know where you can find a shiny Poliwag! Surf the water north of Violet City.
You mean Soul Silver? Silver was the old game and I can't help you with that. However, in Soul Silver you can give shards to the guy in Violet or Fuschia city and he will give you something for it.