You are not able to reset the clock in Pokémon Crystal. You can only do this in Pokémon Gold/Silver.
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Actually you can reset the clock. Under the title screen, press Select+Down+B. The game will prompt you to reset the clock. However, it will require a password which depends on your savegame factors such as name, money, and trainer ID. This site will tell you how to calculate that password: http://www.geocities.com/thelegendarydogs/faqs/gsc/time/timereset.htm
In Pokemon Crystal.
What the hell is a Pokemon crystal
You can't get Moltres in Pokemon Crystal, Only in Pokemon Leafgreen and Pokemon Firered. Including Pokemon Platinum.
When you change your DS's time Soulsilver/Heartgold automatically changes to the DS's time setting. You can check the Pokegear's clock.