Phione, it's just another slot in the Pokédex. It's weaker than Manaphy and they're both useless. The lake Trio are pointless to me too, they're like the same Pokémon with the same type, only with different stats. They could have at least made them Ice/Water, Fire and Electric, but no.
The genie Trio are just ugly, they look too much like a human, and maybe they tried to make it up with their therian forms, but it didn't help that much. I mean, Tornadus is a bird with a freaking mustache xD
Genesect, it's a bug that has lived for thousands of years. I never thought they would actually make a Cockroach Pokémon xD. At least it doesn't look like one. And Keldeo. No comments, I just don't like it.