> If you are assuming that the affection values of those Pokémon will not reset once you give them to your Trainer in Omega Ruby/Alpha Sapphire, you'd be wrong. It is tied to the Trainer ID of the Original Trainer, they will be reset once you trade them. However, if you trade them back to your game you raised them in, they will still retain their affection.
In a nutshell: Affection is tied to Trainer ID, which resets once said Pokémon is traded away, but will retain affection if they are traded back.
Yes, as affection is linked to a Trainer's ID, it will go down if you trade or transfer it to a different trainer. However, if you trade or transfer it back to the original trainer, the Pokemon's affection will go back to the affection it had when it was first traded away.
Gosh hecking darn it I didn't look hard enough on Bulbapedia before going to a different source.
However, if the Pokémon is sent to Pokémon Bank, and into a different version, it will retain its Affection.