"Full Freeze: A Full Freeze is the freezing of the entirety of the Pokemon's Body. With the exception of a few attacks like Flame Wheel and other full body Fire-type attacks, when a Pokemon is Fully Frozen only an opponent's attack will be able to free it, or it will have to wait two (2) actions to thaw. Smaller Pokemon are much easier to fully freeze than larger ones. Full Freeze is only brought on by Blizzard, however successive Ice Beams can have the same effect. In Hail, all Ice Attacks with the freeze effect will cause Full Freeze."
-Referee Training Grounds