No. The underground is only in Pearl, Diamond and Platinum.
The Underground is unavailable in HeartGold and SoulSilver versions
You can only go to Johto and Kanto in Pokemon Heartgold and Soulsilver
You cannot go to the Sinnoh region in "Pokémon HeartGold" and "Pokémon SoulSilver."
there is a Nintendo event maybe at gamestop and go to it with Pokemon heartgold and soulsilver and there you will get celibi
to find Blue in HeartGold or SoulSilver go to Cinabar Island next to Seafoam Island and go right next to the Pokemon center.
You cannot go underground as you were able to in Pokemon Diamond and Pearl. You are stuck above ground in Pokemon SoulSilver. You get two regions to go between, though.
go to release
go to psypokes.com they have walkthroughs for all Pokemon games.
you can't go to hoenn in Pokemon heartgold/soulsiver...
I think your talking about HeartGold/SoulSilver. In Pokemon HeartGold/SoulSilver you're not capable of going to the Sinnoh region, only Jhoto and Kanto are avaliable.
you can only go to kanto and johto
preordering is buying something before it's released and they mail it to you on or after the releasedate...To preorder Pokemon heartgold and/or soulsilver go to http://www.play-asia.com/