Freeze is an effect in Super Smash Flash 2 which causes the opponent to be encased in a block of ice, unable to move for a brief period of time. Mashing the attack button and/or the special button shortens the time spent in the block of ice. Damage has no correlation with time frozen.
Playing with the Freeze modifier in Special versus makes every attack have the freezing effect.
Prior to v0.9a of the demo, it was planned for certain characters to have unique frozen state effects instead of the standard block of ice. However, Sonic was the only character to have this realized.