To trade Pokemon from Pokemon Crystal version to another version of Crystal you need to use a link cable. You can also battle this way.
You can trade all between Gold, Silver & Crystal.
Crystal can only trade between silver gold and red blue and yellow.
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.
In Crystal? No.
No, it is impossible to trade from crystal to ruby/saphire/emerald. The games are incompatible.
I hear you can trade from crystal to sapphire. You have to have two gameboy advances, a gba link cable, and in crystal you have to go to the time machine.
If you can trade Pokemon from crystal version to gold version my guess is yes
Yes but don't trade pokemon only from crystal to red for example don't trade a lugia in red or else ur game will get messed up but u can trade any other pokemon that were in red from ur crystal
NO
No.
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.
No, Pokémon Crystal is not capable of communicating with Pokémon Emerald.