no you can't,it tells you when you trade from the sp to ds. You can only trade pokemon from your sp to ds and once traded to the ds can not be returned to your sp
yes, Pokemon can be traded from different games by using Gameboy Advance SP. But Yellow can not trade with Crystal. Almost all of them from different regions cant.
yes you can
Yes.
No, actually you have to have a Game Boy Color to do that.
Yes, but you need a GBA or SP, DS doesn't have a trade port.
yes
You can with a normal link cable
ask Dr.Phil
You can trade pokémon by using a link cable between your GBA sp / GBA.
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.
Because it can't