All you have to do is grab it by coming up from behind. Use the branches on the ground to change the direction of where the Fargetch'd is looking.
they are on route 47 you have to use water fall to get to them.Hope i helped:D
viridian forest
you have to catch them in the forest of picachu
You catch one in vidarian forest.
In Pokemon Soulsilver you catch pickachu in the Viridian Forest during the day.
chase it and catch it from behind
forest area safari zone
go to ilex forest dumbo!
you can catch it almost anywhere there is a forest or a garden. Its a very common Pokemon and easy to find.
To catch Pikachu in Pokemon SoulSilver, you must go to Viridian Forest in the Kanto region and search in the grass. They are a bit uncommon, so it may take a while.
You can't catch bastiodon in Pokemon soulsilver.
I don't think you can actually catch a pichu but you can catch a pikachu at Viridian Forest and breed it with a ditto.