I believe that you can only trade with the Diamond, Pearl and Platinum versions, but if you have the booklet you get when you buy the game you can find it in that booklet so you can check.
Yes when you complete your game
Just to have more than one pokemon.
Trade from pokemon soul silver or another pokemon game
Yes you can trade Pokemon from Pokemon silver to Pokemon blue. The only restrictions on this is that you can not trade any of the new Pokemon that are introduced in the newer game (Pokemon with the number 151 and up can not be traded to Pokemon blue).
you need to games of any pokemon game to trade
yes you can only if you have a link cable for both, no new Pokemon from the gold, silver, or crystal (meaning no other Pokemon except from the older versions), and in gold, silver, crystal must have 4th badge, talked to bill in that town, and waited 1 day.
Yes, Pokemon Red can trade with Red, Blue, Yellow, Gold, Silver and Crystal.
You have to transfer it from an older game or trade with someone.
you cant because leafgreen is an older game then Pokemon pearl plus its a gameboy advance game.
I'm not sure there is a way to trade Pokemon from and GB game to a DS game. They obviously don't work with the dual slot feature. I'm going to say 'no' but there might be indirect ways to do it.
You have to trade it to another Pokemon game while it is holding a metal coat then trade it back and you will have it evolved.
I don't think you can because 'Pokemon silver' game cartridge is bigger than 'Pokemon ruby' and so you couldn't do it.* *because the cable to trade, is a long thingy, whereas a ruby game cable is a semi- circle thingy.