The Ice Climbers are unique in that they are 2 characters in 1. The partner climber (Nana, by default) is CPU-controlled and follows the player's actions, attacking alongside the leader. When separate, the AI will guide Nana to Popo. During this time, they are not synchronized, or "desynched", meaning Nana will not follow any player inputs until she gets within a certain distance of him.
Desynching can also be manually triggered without having to separate them. This is partially due to how Nana has a several frame delay during most inputs, and from having slightly different attributes from Popo: jump height, gravity, fall speed, and dash (as of Ultimate). Specific maneuvers take advantage of these by using specific means, the most common being during grabs to allow Nana to attack a captive opponent or regrab them (though this particular method no longer applies in Ultimate due to changes made to grabs). Desynching can allow the player to perform an attack, move, jump, or wavedash with either Nana or Popo, whilst inputting a different command to the other Ice Climber, which can allow for highly damaging combos and zero-to-death strings.
There are several kinds of desync that differ in execution. Most methods differ by game.
One exception that doesn't use IASA frames is standing grab and/or dash grab. Once initiated with either of these, the player should buffer grab. The moment Popo's hand goes for the grab, the Control Stick should be set to neutral, the grab button released, and a buffered pummel be inputted. Then, immediately press and hold any button while smashing the stick in any direction. This takes a single input for both Ice Climbers, meaning any direction the player wants to smash in they must also throw.
Below are a few examples of combos that can be done with this desync method:
As demonstrated in Two Climbers, Two Hands, continuous desych is a technique and strategy which involves keeping the Climbers desynced for extended periods of time. In addition to making the Climbers much more powerful offensively, they also become harder to approach with continuous desynch. Due to the extreme difficulty of timing and maintaining a continuous string of attacks, the in-combat potential of this approach is clearly substantial, but largely untapped.
There are 2 rules when keeping the Ice Climbers continuously desynched:
Since its inception, desynching has become synonymous with the identity of the Ice Climbers as characters. The technique's impact on their metagame cannot be understated, with it revolutionizing their neutral and combo game. Many believe they would be completely unviable without them, with ChuDat popularly describing his use of them as "controlling two characters at once". The prevalence of desyncs in every aspect of Ice Climbers gameplay has given the characters a reputation for being exceedingly hard to use at a competitive level, often being looked at as a challenge by budding players. However, it has also caused some to dislike the Ice Climbers, usually citing the reward not being enough for getting good with them.