Either they're hacked, you're using legendaries, or you defied some clause in effect, most likely the no-duplicate-item clause.
[agelimit]competent competitors[/agelimit]
Ichida, the Zealous Blue Partizan
Pearl Battle Record: 105-26
Battle Style: 6v6 Lv100 Singles, No Hacks, Ubers or Legendaries

To gamingly entertain the crap out of you. Yes, I said 'gamingly.'