Freezing is an issue present in Super Smash Bros. 4 and Super Smash Bros. Ultimate’s artificial intelligence; specifically, the AI used to control amiibo. Although the term remains identical between both games, freezing refers to two separate issues in each title.
In Super Smash Bros. 4
In Super Smash Bros. 4, amiibo often walk up to each other and stop moving entirely as if staring at each other. After several seconds of standing still, they will begin moving again. This is a regular occurrence and only happens against other amiibo; they do not freeze against human players. In other words, freezing is not a game-breaking problem for amiibo; it rarely plays into the outcome of a match. Notably, Glenn trained his Olimar amiibo to stand still and was successful; as a result, this Olimar would stand still for the entirety of the match and use its Autoheal bonus effects to time out the game and win in Sudden Death.
In Super Smash Bros. Ultimate
In Super Smash Bros. Ultimate, amiibo no longer “stare” at each other; instead, freezing is an entirely separate problem that is caused by taunting while training the amiibo. amiibo who are trained to taunt (even if only after getting a KO) often freeze and will not block, dodge, or attack for up to a minute. The opponent then charges up a smash attack and gets a free hit. The only way to stop an amiibo from freezing is to stop taunting.