I've never tested that but I think there wouldn't be trouble since it's an "evolution"
btw I saw that if you make evolve a Pokemon into the same Pokemon unchanged, it become temporarly white until the end of the scene ( a battle for exemple )
Depends on your choice on the evolved Pokemon, for me I chose Mega Manectric for base and for evolution, so he won't change.
Another thing is when you get petrified by Nuzleaf, you can see the base Pokemon as a stone statue (exemple Charmander), not the Pokemon that you have but it doesn't matter since you keep the modified Pokemon.