After beating the 8 Gyms of Kanto you have to talk to prof. oak and then he will tell the guards to let you in.
yes
you go talk to prof. Oak
Mt. Silver is west of the Indigo Plateau gate in Pokémon HeartGold and Pokémon SoulSilver.
Go to professor oak and get Hm8 rock climb than permission to go to Mtsilver to challenge both ash's dad and a legendary pokemon!
beat the league
At Mt.Silver, you will find Pokemon at least level 50 to level 60. They are very tough, so try to catch one. At the peek, there is a trainer named Red. He has Pokemon for level 80 to level 88. His pikachu is the best in the game. Hope I Helped. : )
Moltas: the fire legendary bird Pokemon the second strongest bird Pokemon
To get to Mt Silver you have to defeat the Pokemon league and all of kanto's Gyms.
To get to Mt. Silver, you fly to Victory Road. Go inside the building thingy and go out the left exit. Keep going left thru the grass and at the top of Mt. Silver is Red, (a.k.a. Ash Ketchum) :D
There is no best Pokemon on Pokemon HeartGold.
there is no Pokemon Mansion in Heartgold.
They are not in Pokemon HeartGold