I mean in XY. They give him three Pokemon that are weak against electric types, Hawlucha, Froakie, now Frogadier, and Fletchling, now Fletchinder. Why the heck do they give him Hawlucha?! He's ugly, and terrible! Sorry to those who like him, I just hate him. And then they give him Goomy?! What the heck were the writers thinking?! It said so itself in the episode that Goomy was the worst dragon type!
Most likely because of the same reason they decided to throw out Charizard, a show isn't fun if there is no challange. In any medium, if there is no challange or difficulty it would be incredibly boring. Having those Pokemon could simple be about showcasing the new Pokemon.