I believe we will not have a third person in the group of characters in the new anime based on the games pokémon X and Y.
Nintendo showed the trailer of the new games X and Y and I have not seen any major character in it.
I just saw the main characters of X and Y, who are the characters we control.
I believe in the new season we have only 3 characters are Ash, Pikachu and the XY girl.
If Ash will have a new rival I do not know, probably he will have a rival. I say this because in Best Wishes he had one.
Nintendo and Game Freak will want to promote their new games Pokémon X & Y, then I think the writers of the anime will put the new girl Pokémon X & Y with Ash in the anime.
Just as they did with May, Dawn and Iris.
Definitely going to have a new team of villains, was just in all seasons.
All this according to the plot that the body will have games.
Pikachu is a character loved by Japanese fans, the proof is that we have a number of short films and have a Pikachu with the new Eevee evolutions and Sylveon.
Sylveon can be a great Pokémon to the xy girl.
A beautiful Pokémon for a beautiful girl!!!
The writers will want to show the new character, then for sure she will have a story!!
A nice story, of course! To you assist there.