You have to get the Aurora Ticket from a Nintendo Event and head to Birth Island to solve the puzzle. I've never been to the island before, so I don't know how to solve the puzzle. Sorry. Oh, and in order to get the ticket, you must have the Mystery Gift option available in the pre-game menu. Just head to a Pokemon Mart and fill out the questionnaire with "LINK TOGETHER WITH ALL" to get it. Once you have that, simply access Mystery Gift and select the ticket from the Wonder Gift option. However, in order to get the ticket under the Wonder Gift option, you must hook up to a Wonder Spot at a Nintendo Event. So it's back to square one. Sorry.
you cant
in a fossil
You can't you just have to use cheats
Hacking/Cheating or legit pokemon event that will give you the ticket to go to birth island
To get Pokemon firered on PC download a vba and Pokemon firered ROM
Buy iCheat
You can catch a Ho-Oh at Navel Rock in Pokemon FireRed.
You can catch Moltres at Mt. Ember Peak in FireRed.
you can not catch him
You cannot get it in Pokemon FireRed. It doesn't matter because it is not necessary in Pokemon FireRed.
you can't catch any hoenn Pokemon in firered or leafgreen you must trade hoenn Pokemon from ruby or sapphire or emerald to leafgreen or firered.
You cannot catch it on Pokemon firered only on diamond pearl and thhe new one Pokemon platinum