Egg.
No you cannot catch Larvitar in Pokémon Emerald.
Larvitar cannot be obtained unless you trade it from leafgreen or firered.
Trade from Firered or Leafgreen.
Yes, if you trade it you will automatically get the national pokedex on Pokemon Emerald
Trading is required since it's not obtainable in the game.
Larvitar is not in Ruby/Sapphire/Emerald naturally. However, you can get a typhlosion if you trade it from Pokemon Colloseum.
you can get the national dex from prof. birch after deafting the the elite four. then you can trade larvitar from leafgreen or firered. you can find larvitar in the seventh island in leafgreen/firered
Nowhere, because you can't find one in Emerald. You'll have to trade one from FireRed/LeafGreen.
use poke radar at certain routes
Red version was not made to migrate with emerald.
No. In Pokemon Emerald Version, you can only obtain Pokemon from generations 1, 2 and 3.
No.