For example, if I evolved Omanyte to Omastar in Pokemon Yellow and then transfer it to Pokemon Bank, will I have both National Pokedex entries for Omanyte and Omastar in my Pokemon Bank, even if I only have an Omastar now?
For exemple I trade alakazam for dratini
My data will have dratini like own but not caught
the trader will have alakazam own too but no caugh
You will keep alakazam data and your trader will keep dratini data
So nothing change you wil still have your pok by caugh and have new pok by own
hope it will help