They tell you where Pokemon are and where Pokemon swarms are.
To tell a shiny from a normal well... first a shiny will have a sparkle in battle and it is a brighter different colour then the original pokemon Example mew is pink shiny mew is blue.
There is no way of telling if a Pokemon in an egg is shiny until it hatches. Sorry.
I have Dragonite..... Can you give me Rayquaza? If you can tell me by msn----->[email protected]
it will be a different colour from usual and when you first go into battle there will be a ring of sparkles around it. Also, you can check by going to the Pokemon you want to check to see if its shiny and go to its summary. If there is a little red star next to the Pokemon, then it is shiny.