I think Chespin's final evo will be more a physical tank spread, and with a Grass/Steel typing, making him very good for that role (a 4x Fire weakness, 2x Fighting weakness). It will probably be a good user of the Sub/Seed strategy.
Froakie, if going the way of a wizard, will probably be high in Special Attack and Special defense but has the physical defense of wet tissue paper. He might be more wallish than the others, being able to learn a variety of status-altering moves and Recover. He'll probably be Water/Psychic.