Psulidon was a Latias Jared obtained in his Alpha Sapphire Nuzlocke series. Jared was against using Psulison, felling she'd be too strong at the point in the game he was at, but Jared eventually decided to keep her boxed for the time being, saying that he may use her later if she's required.
This time never came though, mainly because Jared whited-out to Winona, Fortree City's Gym Leader. And so, Psulison stayed in the box, never to leave.