Team Rocket's captures during Unova were powerful Pokémon that didn't seem to have any kind of bond with their trainers, Jessie and James, which everyone disliked, as Jessie and James have shown in the past that they care a lot about their Pokémon. Moreover, their personalities were also pretty much inexistent. The only Pokémon which seems to be partly an exception is James's Yamask, though it was only in the beginning of his journey with James.
Now, let's think about it: powerful Pokémon that had absolutely no bond with their trainers. Doesn't it remind you of standard villain Pokémon? Those kind of Pokémon that Cassidy and Butch carry with them, those Pokémon that seem to be rented.
So... Having in mind the events of last episode, with Jessie and James giving their four Unova Pokémon to Giovanni without any trace of sadness, doesn't it make you think that maybe those Pokémon were boring on purpose? So that one wouldn't feel sorry for their disappearance. I got surprised when I saw that they gave their Pokémon, but as soon as I remembered "wait, I don't have any kind of affection for those Pokémon" I thought that it was an original way to get rid of their Pokémon (maybe forever).
What do you think? Did their "release" affect you in any way? Was it good or lazy writing?