If you go to the gym, you will find a woman blocking the way. She tells you
that Whitney, the Gym leader, is at the Radio Tower on the west side of
Goldenrod. Head to the radio tower and talk to the attendant next to Whitney.
http://www.gamershell.com/faqs/pokemonheartgoldversionfaqwalkthrough/1.03/
you need the pokeflute
go to the Pokemon league. there is a room where a guy "checks" to see if you have all 8 badges. in that room, there are these 2 guys blocking two paths. the guy on the left is blocking mt.silver
The Pokemon bocking your way is a Sudowoodo. To battle the Sudowoodo, you must use the Squirt Bottle on it.
Go get a starter first.
After you beat red
if you know the sudowoodo blocking the way u have to battle it and catch it
You'll need the HM Whirlpool and teach it to one of your Pokemon and you can pass the Whirlpools blocking Whirlpool Cave.
To move the guy blocking Mt. Silver , beat all 16 gyms and talk to Prof. Oak
you need all of the gym bades
In Pokemon silver after you get the expn card you will get a Pokemon flute melody on the last line of your radio which you can use to awaken the sleeping snorlax blocking the way to the cave that leads to Pewter city
If you are reffering to the ones blocking the Kanto and Mnt. Silver all you need to do is beat the Elite 4.
You first have to beat the Elite Four for the first time and then you have to get all of the Kanto Badges and he'll let you pass