you have to see all the Pokemon through 150 then talk to professor oak
there is no national dex in Pokemon emerald. but, you can trade it from Pokemon leafgreen, and firered.
No
catch all of the Pokemon in the kanto region then go and see pro. oak and he will give you the National Dex
when you beat the elite four and have 100 Pokemon go to professor oak and he will give you and Gary the national dex
The Sevii Islands(islands 4,5,6,7)
If you get squitle as your starter, once you get the national dex, it will be a roaming Pokemon
you cant find it you have to migrate it from Pokemon leafgreen or Pokemon firered.
Get the national dex and beat the elite 4.
In Pokemon fire red the national dex looks the same as the kanto dex but it lets you travel above 150 if you have caught or seen one Pokemon from #150-386.
you have to mirate growlif from Pokemon firered. To get growlif in firered you need the national dex then you can catch it on route 2.
You can only unlock the national dex that will add to the wild pokemon you see on the islands 4 - 8 , therefore you have to trade with saphire to get them added to your national dex
After you fill your whole dex and beat the E4.