HeartGold defiantly
actually, It's opinion. so whichever is best will vary from person to person. I too think It's Heartgold or Soulsilver though.
Of course soul silver is better. With thepokewalker it's a way to get a variety of pokemon. Also there kanto
correct me if im mistaken but if you take silver and firered for example and trade them then u firered to diamond
Soul Silver will, but the original GBC Silver cannot.
Blackthorne city is not in Pokemon Diamond but in Pokemon Heart Gold/Soul Silver
same as diamond and pearl,
Trade from pokemon soul silver or another pokemon game
you can not you can only get it in diamond and pearl
Migrate in from Pokemon gold/silver
No
Go to the Union Room.
pokemon diamond pokemon pearl pokemon platnium pokemon heartgold pokemon soul silver
Transfer it from Pokemon Diamond and Pearl.