[Edited by petron113, 10/5/2008 2:30:48 PM]
To get a Gamshark go to this link: Link
For the first one you can make them stop when you reach Rayquaza on the top of the sky piller you can find it on route 131.
About game shark you can buy from some game shops, you can also buy it from Internet and yes it'll be shipped, I think =/.
A Gameshark is a little device that you put codes into, and it glitches your game (in a good way) to make certain cheats, such as: All Wild Pokemon are Rayquaza.