Question

Did pokemon's cries change over the generations?

Answer 1

Nope. None of them do.

EXCEPT:

>Pikachu is the only Pokémon to have its cry changed without changing forms. In Pokémon Yellow, Pikachu's cry is actually provided by Ikue Ohtani. This is also the case if the starter Pikachu from Yellow is brought to battle in Pokémon Stadium or Pokémon Stadium 2.

Pikachu's cry was different in Yellow and the Stadium games.

Answer 2

Some cries have changed in X and Y and for Pokemon Stadium just for one example here is bulbasaur's cry http://www.youtube.com/watch?v=0nXOg0Tntio&feature=results_main&playnext=1&list=PL8483DC5C21BAB3A4