>>19317299More info on designs:
Masuda has said that they first come up with the concept of the pokémon, the place where it should live, they things he'd do to survive or to interact with the environment (all of this first considering the major theme of the region) and then they draw it accordingly and put him moves and abilitites.
In other cases it is the competitive scene that inspires the pokémon or that changes their initial concepts.
So designers dont have freedom to do whatever they want, they must stick to the general plans.
An example of the later is how Frillish and Jellicent were pure water types at first and Ibe was later forced to change to Water/Ghost, something she didnt like because she wanted them to be cute, another is how Hyderigon was initially going to be Dragon/Steel (and it still maintained those tank-like strips in his body after the change to dark).
I've been reading lots of interviews the last 3 gens, too bad not all of them are in English