You can trade all between Gold, Silver & Crystal.
If you can trade Pokemon from crystal version to gold version my guess is yes
Crystal can only trade between silver gold and red blue and yellow.
Yes
There is no NPC who you can trade a Haunter to for a Gengar in Pokemon Crystal. To get Gengar you will need to trade with another player or a copy of Pokemon Gold, Silver or Crystal.
Trade it from Crystal gold or silver
trade it from silver, gold :(
You can trade with Pokémon Red, Blue, Yellow, Gold, Silver and Crystal.
Silver, Crystal, Red, Blue, Yellow, and another Gold
Ask someone with a copy of Red/Blue/Yellow/Gold/Silver/Crystal to trade with you. Have them trade any Pokemon with you, and then trade the now-evolved Machamp back to you.
Yes
It will let you trade between Pokemon Gold and Crystal. You just have to make sure you are using two gameboy colours and a gameboy colour link cable.
no you will have to evolve a gold onix but you have to trade the gold onix with the metal coat and it needs to be happy while being traded.