Gender bender

A gender bender is a situation where a character instantly switches genders. It is usually used in comedy, although there are some dramatic stories that may use this particular trope.

In mainstream Smurfs media, Hogatha in the cartoon show adaptation of "The Fake Smurf" switches genders when she becomes a fake Smurf. Brainy in the episode "Monster Smurfs" briefly becomes Smurfette through the use of Papa Smurf's magic powder, but whether he truly became a Smurfette in more than appearance is uncertain.

Hero: The Guardian Smurf
In the HERO: The Guardian Smurf adaptation of the cartoon show episode "The Magic Egg", Hero accidentally becomes a Smurfette when he strikes the magic egg, saying that he's a Smurfette if any of his fellow Smurfs are truly him.