I've beaten the game with Shinx and Riolu, and I followed the storyline and I am stuck on Mt Travail. Can anyone help? Being awkard, it won't let me take Shaymin or Drifloon in.

Well, all I do is kinda "wait it out". You see, when I get stuck, I just stop with the storyone and do missions for a while. Manliy ones with rewards like Poke or Reviver seeds. Keep doing that, then try again. Does that help?