Mt. Silver is west of the Indigo Plateau gate in Pokémon HeartGold and Pokémon SoulSilver.
you need all the 16 gym badges and then go through the cave
Union Cave.
There is no Unknown Cave!!
There is no Carmen Cave.
in the cave!
Cerulean Cave.
all you have to do is get the kanto radio and put the little dot in the middle top and the Pokemon near diglett's cave will wake up and you will need to battle it and then you get threw the cave
Youse can't. It be impossible. U got to trade into Pokemon platinum version and lvl it up at a certain cave, but me forget what cave it be. Sorry. You level it up in Mt. Coronet / Chargestone Cave. - Cooldude335 -
There is one in Cerulean Cave.
Cerulean cave
In Diglett's Cave.