Any Pokemon you want to trade to the other game
you can not trade crystel with ruby because Pokemon cristel is a different generaion than Pokemon rudy
No.
No
Yes after becoming Pokemon champion in both games you can trade but after firered delivers the ruby and sapphire to celio at one island then you can trade.
You can trade from Pokemon Ruby to another Pokemon Ruby using a link cable.
No. Pokemon Blue was for the GameBoy while Pokemon Ruby was for the GameBoyAdvance. The games are not cross compatible.
I'm going to assume you mean "Pokemon Ruby" in your question. Anyway, to trade between Ruby and XD, you must beat Pokemon XD and defeat the champion in Ruby.
Any pokemon from Sapphire, Ruby, and LeafGreen
They should be able to trade.
trade from Ruby/Sapphir trade from Ruby/Sapphir trade from Ruby/Sapphir trade from Ruby/Sapphir
Trade with Ruby.
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.