The attack is a combination of an Ice Beam along with an Aqua Jet. This attack is very difficult, but once mastered, can deal a lot of damage and gain many appeal points. Its disadvantages are a low accuracy and the need for a partner to perform. Only Ash's Buizel knows this move.
It was first accidently used when Dawn's Buneary used Ice Beam on Buizel, freezing its Aqua Jet. After that accident, Buizel said to Dawn that it wanted to perfect that move. Zoey also mentioned that the move was really perfected when Ash ordered Buizel to use Ice Aqua Jet with the help of Candice's Abomasnow's Blizzard.
However, it doesn't really need a partner to perform, and can also be used, with good timing, with an enemy's Ice Beam, as seen when Buizel used it when it was battling in the Sinnoh League.