Ebay would work well if you don't put a big price on it
20 bucks at the most
At the pokemart
Yes they do
Hack. DO NOT SELL!
You can look at Gamestop.
If you mean Unkown as in the pokemon, you can't.
Sell everything you have, but that won't get near it.
There is currently no ChaosBlack version in the US, but you probably wouldn't want a fake game anyway. Also, it is illegal to hack a game and sell it as your own. That's what ChaosBlack is: a hacked FireRed/LeafGreen game.
The Department Store in Celadon City sells fire, water, thunder, and leaf stones. You can purchase them on the fourth floor. Note that the store does not sell sun or moon stones.
No
A mere Cameo appearance from Firered and Leafgreen. They do no good, so you may as well sell them.
You can sell it to this chef inside a trailer on route 5.