No. You have to migrate six Pokemon from GBA games once you reach Fuchsia City.
catch him in heartgold/soul silver and trade over or migrate from firered/leafgrean. Hope this helps.
No.
no you can not, you can only get ho-oh in Pokemon heart gold or soul silver, or you can get it in global trade.
No silver is not compatible with firered.
== ==trade it from silver
you can get mewtwo more than once if you get it in firered or leafgreen and trade it via pal park
its in the same location as it is in firered and leafgreen
heart gold and soul silver
sorry you have to trade it to Pokemon soul silver
trade
Yes it's possible. Just like you could trade Mewtwo from FireRed/LeafGreen for Rayquaza from Ruby/Sapphire/Emerald for example.
Soul Silver: route 36 Heart Gold: trade with Soul Silver