You can't.
You can't get to the johto region in firered.
You can't go to Johto in Pokemon FireRed or LeafGreen.
You can't.
you cant, sorry.
Whirl islands are in the johto region which is not in firered.
Yes, after beating the Elite Four, they will be roaming Kanto.
The johto Pokemon from FireRed, LeafGreen, and Emerald can be migrated to the DS. but the older games such as silver and gold do not fit in the DS.
Not any hoenn Pokemon but firered and leafgreen can catch alot of kanto and johto Pokemon ruby and sapphire can and can't.
You can only trade it from the Johto region or the Hoen Region.
All hoenn pokemon, some kanto and some johto examples include magmar and mantine.
Actually, I think that is a Johto region pokemon, and seeing as Firered is a 1st gen remake, which is set in Kanto, you can't find it in the wild. You might be able to trade for it.
you cannot unfortunetly fire red is only hoen kanto and johto Pokemon not sinnoh.