You need to beat the 8 gym leaders in Kanto and then go to professer Oaks research center and he will make an arrangement so the guard to the left at the Pokemon League Reception gate will let you pass and then your on your way to Mt. Moon
Moltres.
Red is not in Mt. Moon; he is at the top of Mt. Silver.
In Pokemon HeartGold and SoulSilver, you can go through Mt. Moon, but the cave is very small and can be explored through in five minutes with Pokemon repellent.
First you have to catch Mewtwo and then head to Mt Moon at midnight on Monday. Somewhere deep in the cave is were the deoxys are.
Kanto Routes 13, 14, 15, and Mt. Moon
That depends. Pokedex: Your rival at Mt. Moon. For your own: Trade a Kadabra.
He goes to the Pokemon league. after that he goes to mt. moon or at least that's what happened to me.
Pokemon league After beating him in mt moon Go up the stairs Untill your rival comes NOTE: he is only there on certain days this also works for heart gold
Go to mt. moon on diffrent days and run around in the cave a you might run into a clearify
Mt. Silver
Mt. Silver
at the top of mt. silver.