I actually quite like the POkemon selection. none of them are super stereotypical, and each pretty much suit the trainer that owns them.
Castform being with Cheren is neat. Castform was made by humans, and with Cheren being obsessed with the pursuit of knowledge he pretty much fits being a Castform trainer.
Tauros may be a bit manly for Whitney, but then again, her anime counterpart is pretty butch herself, and Whitney finally learns how to toughen up a bit after you defeat her in HG/SS. Maybe her getting tough is the reason why she got a rough, gruff Tauros.
I quite like the Fire, Water, and Grass specialists having a starter from their hometown region. It's like an ode to their home, and almost as a little gesture that they too started with the three starters (though that may not be the case, it's still a cute gesture).
Plus, their aren't that many Dragon, Ice, or Ghost type Pokemon. It'd be hard for them to give each person a somewhat unique team without ALL of the teams being the exact same thing.