So, hypothetical here.
Say a Raltz is given to a little four or five year old girl and eventually evolves in to a Gardevoir long before the little girl reaches ten years old. Said little girl rarely sees her parents and spends most of her days perfectly alone with the Pokemon.

How would the evolution affect the relationship between the trainer-to-be and Gardevoir?

Would the Gardevoir disobey her when she became of age to become a licensed Pokemon trainer?

How would the Gardevoir feel about being taller than the little girl? Would the status quo alter from a sisterly friendship to a more maternal thing?