The only thing that jumps out at me is the fact that Xerneas is a legendary, but that's only relevant to specific formats, which the term "free play" would not correlate to. This would likely indicate that you have an illegal move or ability on one of you Pokemon, resulting from hacking by either you, or someone else through the ancestor of one of your Pokemon, obtained through a trade. I don't see any illegal move combinations though. Can't say for Abilities as you did not list them.
Are you only using 5? And what is Salamance's item?