When used, Lucario enters a defensive tai chi-like stance. If it is attacked during this stance, it will teleport, then strike with a sliding kick from the left or right (depending on the direction the analog stick is held in) for moderate damage and surprisingly high knockback, which is even greater when Lucario has taken damage. If Lucario successfully counters with Double Team near an edge, it may teleport above the ledge and fall downwards as it unsuccessfully attacks, making recovery difficult.
Double Team has a longer length than Marth's and Ike's Counter, having the longest counter window in Smash 4 at 35 frames (tied with Vision), which also comes out the fastest, at 5 frames (tied with Slip Counter and Witch Time). To compensate, it has the longest overall animation for a counter, being over 40 frames long after the counter frames. It is notably different in that it does not change power depending on the countered move; rather, it does a constant attack no matter what moves it counters. One of the most interesting features of Double Team is its intangibility, which lasts until the counter frames end, leaving him unaffected even by attacks that cannot be countered, such as grabs and Final Smashes.
Additionally, if Lucario is hit during a Double Team and goes into the counter strike, Lucario will not have a hurtbox until it completes the counter attack. Double Team also reduces Lucario's falling speed for a minor duration. This move is rather easy to dodge, as it is possible to air dodge or shield the attack when Lucario disappears. Being an Aura based attack, in Brawl, it does 7% at percents below 20% and at 170% or higher it deals 15%. In Smash 4, it can deal as little as 7.26% at 0%, or as much as 18.7% above 190%.
Note that Lucario actually strikes the location around where it was hit, just like Counter does. If Double Team is used on a ranged attack or an attack that causes its user to move quickly (Spin Dash, Rollout, etc.), Lucario will most likely miss with its counter attack.
Double Team is rather useful in Boss Battles mode to dodge boss attacks. While it isn't guaranteed to hit the boss (and even then, it doesn't deal much damage), it is a quicker way to dodge than a roll, short hopped air dodge, or just running away, and it has longer duration than a sidestep.
In Smash 4, the counterattack portion of Double Team has an aesthetic change where Lucario leans away from the direction he is facing, as well as making the attack resemble more of a flying kick. The kick also travels much further at higher percentages when affected by Aura.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
In the Pokémon games, Double Team is a Normal-type status move introduced in Generation I that raises evasion by one stage, making it more likely for attacks to miss the user, and can be stacked for even larger evasion boosts. The move does not act like a counterattack like it does in the Smash Bros. games. It is generally banned by unoffocial competitive circuits for its reliance on luck and its difficulty to counter effectively when paired with Baton Pass, making Double Team and similar moves very infamous among players. The animation in Brawl is similar to the animation in the Pokémon games (notably ones like Pokémon Battle Revolution or Pokémon Colosseum).
Lucario can learn Double Team in all games it appears in via TM32 until Pokémon Sword and Shield. The Japanese name of the move contains the term "bunshin" (分身 or 分進), with the former meaning "other self/clone", and the latter meaning to "divide and/or advance".