There is no underground tunnel.
You cannot go unlock the Underground Path in HG/SS because you don't actually need it, since you can go through Saffron City.
LeafGreen- UNLOCK KANTO REGION FireRed - UNLOCK KANTO REGION Emerald - UNLOCK HOENN REGION Saphire - UNLOCK HOENN REGION Ruby - UNLOCK HOENN REGION SoulSilver - WHY TRADE WITH YOUR SELF,(Yes You can always trade with SS/HG) HeartGold- WHY TRADE WITH YOUR SELF,(Yes You can always trade with SS/HG) Pearl - ALWAYS AVAILABLE TO TRADE Diomond - ALWAYS AVAILIBLE TO TRADE -Twiinkle *THE SECOND POKEMASTER*
so you can get to kanto
if your on ss/ gg there isnt
once you beat the elite four, you go back the the lab and get the SS ticket. take the boat and you'll end up in vermillion
in ss, he is somewhere in cerulian cave... but if you want to go there,you have to get ALL of the kanto badges.
there is no ss anne that's in the kanto region. Pokemon platinum is in the sinnoh region.
The SS Anne is not in HeartGold or SoulSilver however when you arrive in Kanto you'll arrive in Vermilion City so you go and challenge the Gym Leader there.
The Underground Path in inaccessible in HG/SS.
It's usually called either the Underground or the Tube.
in the kanto region hope i helped
After you defeat kanto league go to professor elms lab and talk to him,he will give you the SS Aqua pass to go to kanto and you go;after that defeat all the kanto liders.