Pick Your Poison
Unless you have <30 health, Gloomy is never a bad thing. :bUnlucky, you mean :p ; the only time i noticed that was when i played Decopon.
Rewatching the fight, i see it happened only the very first match (the one right after the button check) in the FT3, so i wondered if there were any trick, but yeah, a low probability random chance makes the most sense.
There may still beIf you do rematch in an offline set there is a chance she will start gloomy