I do, in fact think that generation five should be included within the guild, but I believe there may be somethings that need to be touched upon, simply because of the situation with the generation five Pokemon.
For example; generation five Pokemon are supposed to exist on an entirely different continent from the others, and thus it would make sense that they were not in the same area as the current four generations. Quite possibly, introducing their arrival in a chapter? Or if someone wanted them to join their team, maybe they were would to venture to areas overseas? It's a tricky thing to figure out, but it's important to consider, at least.
I, like Amber, Cysic, and Kyle before me, do think that it wouldn't be right to stop people from using the fifth generation. Although there aren't a lot of fifth generation that most of us seem to like, there are a few, and on top of that, opinions, likes, and dislikes vary from person to person.
On top of this; the new abilities and moves. Those moves and abilities will become incorporated into the world of Pokemon everywhere; it would be near impossible to remember every Pokemon's fifth generation moves and abilities, and keep them out. It just wouldn't work, and they might be beneficial to the roleplayers, with new powers and so much to choose from. I honestly know, that I would find it incredibly cool to possibly be able to bring in new moves for the team members I already have.
So. in conclusion, I think that generation five should be included. For the people who like the Pokemon, it's unfair to them. The moves and abilities could be useful, and offer new choices to roleplayers. And not allowing the fifth generation just doesn't make sense as a whole.