There are no 5th to 4th gen transfers. If you meant 4th to 5th gen transfers, I was able to Shift once when I had another family member's DS and with a Japanese 4th gen game. You can also Pokéshift .pkm files with a special program that's floating around the interwebs, but it's far from certain if the result is legal.
As for the trade, I'm going to trade with MeGaMaN X first, also please note that neither Crobat or Porygon2 are redistributable.