Prof. Elm is in his lab in New Bark town as soon as you start the game.
Yes, both HeartGold and SoulSilver are on the Nintendo DS
newbark town
You cannot battle Professor Elm. He is there to help you out. He prefers to research than battle.
Continue with the game
You get the pokegear from your mom after you talk to prof elm.
it is only for the DS
Yes, you can. Pokemon HeartGold uses the time from your DS settings. So, change the time on the DS and the time in Pokemon HeartGold will change with it.
profecer elm givs it 2 u
Only on the Nintendo DS, DS lite and DSi
yes,
Yes, a Japanese version of Pokémon HeartGold will work on a DS from Australia. The Nintendo DS can play all games regardless of what country they originate from.
You need to mate the Pokemon with a Ditto.