You need to catch all legendary beasts and have the Rainbow Wing to have access to the Tin Tower, where Ho-Oh resides. Please use the Metal/Color Q&A thread next time! Crystal Version is a part of the Metal generation, not the Advanced. Here's a list of what is in what generation, just for future reference:
Color Generation: Red, Blue, Green, Yellow
Metal Generation: Gold, Silver, Crystal
Advanced Generation: Ruby, Sapphire, Emerald, FireRed, LeafGreen
4th Generation: Diamond, Pearl, Platinum, HeartGold, SoulSilver
5th Generation: Black, White
Hope that helps. :) Good luck with Ho-Oh!
Locked.