Mt. Silver is thought to consist of the most powerful wild Pokemon and is located west of the Indigo Plateau, in between Kanto and Johto. If the player has obtained all sixteen badges in Pokemon HeartGold and Pokemon SoulSilver, they are then allowed to access Mt. Silver. At the very top of the mountain is where Red, the most powerful trainer in the game, is located and will battle the player.
You may also obtain Moltres here by going up the waterfall at the left when you first enter the cave, and that should take you up to Moltres's cave. Keep in mind that you need HM07 or the move waterfall to get past the waterfalls, and once you get to Moltres's cave you'll need the HM Rock Climb which is the last HM of the game to obtain. To get to Mt. Silver you must have the HM's Waterfall, Rock Climb, and Surf which are all obtained through some point in the game.
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