to get the ruby yes you do
Gastly is unobtainable in Pokemon Ruby. You need to trade one from Pokemon Firered or Leafgreen.
You can't in ruby you need to get one from leafgreen or firered.
The HM move cut
Registeel is not catch able in Pokemon LeafGreen. In order to get a Registeel you will need to trade for one from Pokemon Ruby or Sapphire.
The reggis are not available in leafgreen you will need Ruby, Sapphire and Emerald to give you them.
no
If you trade Pokemon between leafgreen and ruby ruby will have your leafgreen Pokemon and leafgreen will have the ruby Pokemon both in the party they will not be sent to the PC unless you personally walk to the PC and do so.
the treasure is the ruby but u can only get it after u catch 60 different Pokemon and get the national dex u need both ruby and sapphire to trade with emerald
you need a link cable EDIT:and two gameboys.
You cannot find Misdreavus in Pokemon Ruby. To get a Misdreavus you need to trade for one from a copy of Pokemon LeafGreen.
Access to the Pal Park Pokemon Ruby, Firered, Leafgreen, Sapphire Or Emerald
There are none in Pokemon Ruby trade from FireRed or LeafGreen.