It was Walrein vs. Blissey, so I don't think they could have. It never seemed to work from full health though. Only when the Blissey was partway down. I don't know if that makes a difference.
I could try to do it again, so I could tell you more certainly, but definitely a level 65 Walrein used Sheer Cold on a Poisoned, partially weakened lvl 100 Blissey in a secret base in Omega Ruby. [[User:Bug Catcher Wade|<span style="color: Purple;">'''Bug Catcher Wade'''</span>]] 05:38, 17 December 2014 (UTC)