That depends. A mod/admin would have to approve what I'm saying, but if you are only showing your team I don't think it matters. Just to say, this could be completely wrong, so wasit for a mod/admin to have the final say. :l
The only forum that it is acceptable to do this is in the Pokemon Challenges forum, since a lot of people who own the actual games play modified versions of them for the sake of challenges (like Nuzlockes or Randomizers). Otherwise, there are no acceptable forums for it to be posted in. Posting such things in the forum for the base game (the unmodified version) would confuse legitimate players, and I don't want to see Pokemon General get polluted with numerous threads talking about unofficial Pokemon games.