It was shedding its skin and Clair was protecting it at that time. When Team Rocket tried to steal Dratini, Clair protected it which led it to evolve into Dragonair.
A † shows that the move was used recently, unless all moves fit this case or there are fewer than five known moves.
In the games
In the Generation II games, Clair has three Dragonair, but they are not her highest-leveled Pokémon; her Kingdra is. In HeartGold and SoulSilver, Clair only has two Dragonair, the third being replaced by a Gyarados.
Clair's Dragonair appeared in the Gold, Silver, & Crystal arc of Pokémon Adventures manga. She has raised it from a Dratini since her childhood. It debuted in the round Debonaire Dragonair, where it was first seen defeating Clair's disciple's Kingdra in a battle. Later, Clair used Dragonair to battle against Suicune, but was defeated when it tricked them into attacking its ice reflection and launched a powerful BubbleBeam.
Clair also used her Dragonair to fight off the brainwashed Team Rocket Grunts aboard the Magnet Train. On the same train, she then used it to battle Blaine and to make him disclose the whereabouts of Lance. However, Dragonair was quickly defeated by Blaine's Entei, and after acknowledging this loss, she sends in the report that Blaine had defeated her.
As a Dratini
Much later, Clair and her Dragonair reappear before Silver, thinking that he had something to do with Lance's disappearance.
A † shows that the move was used recently, unless all moves fit this case or there are fewer than five known moves.
In the Pokémon Pocket Monsters manga
Dragonair in Pokémon Pocket Monsters
Clair's Dragonair debuts in The Ultimate Battle...?! where it becomes the final test for Red's Clefairy. However, since Dragonair is strong, Clefairy has no choice but to work with Tyrogue in order to defeat the Dragon Pokémon.